feat(relationship): editable relationships with LocalDate+DatePrecision dates and notes (#841)

Closes #837

Makes `PersonRelationship` fully editable (type, related person, dates, notes), migrates its dates from `Integer fromYear/toYear` to `LocalDate + DatePrecision` (mirroring the #773 person pattern, ADR-039 / V76), activates the previously-dead `notes` column, and gives the Zeitstrahl's derived **Heirat** events full date precision for free.

Both Open Decisions confirmed as adopted: **no `@Version`** (last-write-wins, single-writer archive) and **`DELETE` ownership-mismatch aligned 403 → 404** (anti-enumeration, matching the new `PUT`).

## What's in it
- **V78** migrates `person_relationships.from_year/to_year` → `from_date`/`to_date` + NOT-NULL `*_date_precision` (default `UNKNOWN`); pre-check abort on corrupt years, `YYYY-01-01`/`YEAR` backfill, 5 named CHECK constraints, year columns dropped.
- **`PUT /api/persons/{id}/relationships/{relId}`** (`@RequirePermission(WRITE_ALL)`) re-runs every create invariant (self / coherence / order / reverse-PARENT_OF / duplicate) and re-flags family membership; orientation preserved per viewpoint.
- New `ErrorCode.INVALID_RELATIONSHIP_DATES` registered in all four sites (§3.6).
- `TimelineEventService` sources the derived marriage date from `SPOUSE_OF.fromDate` + precision.
- Frontend: `RelationshipDateField` (DAY/MONTH/YEAR), upsert-capable `AddRelationshipForm` (pre-fill + notes + in-flight submit lock), `RelationshipChip` Edit affordance, `updateRelationship` server action, read-view date range + notes, `formatRelationshipDateRange` helper. `api.ts` regenerated.
- Docs: ADR-044, db-orm/db-relationships diagrams, DEPLOYMENT §5 deploy note, RTM REQ-001…REQ-019.

## Requirements
All 19 EARS requirements implemented red/green and marked `Done` in `.specify/rtm.md`.

## Test plan
- **Backend** (targeted, green): `RelationshipMigrationTest` (Testcontainers pg16, 8), `RelationshipServiceTest` (22), `RelationshipControllerTest` (15), `RelationshipServiceIntegrationTest` (real DB, 10), `DerivedEventsAssemblyTest` (17), `ArchitectureTest` (14); `clean package` builds.
- **Frontend** (green): `relationshipDates.spec.ts`, `AddRelationshipForm.svelte.spec.ts`, `RelationshipChip.svelte.spec.ts`, `PersonRelationshipsCard.svelte.test.ts`, `page.server.spec.ts`, `messages.spec.ts`. `npm run check` = 798 (below the ~834 baseline); `npm run lint` clean.

## Notes for reviewers
- **Spec deviation:** the edit form was built by making `AddRelationshipForm` upsert-capable rather than a duplicate `EditRelationshipForm` (DRY); RTM rows reference `AddRelationshipForm.svelte.spec.ts`.
- `api.ts` regenerated from the live spec; only relationship-relevant hunks remain (one springdoc `PageableObject` field-reorder pruned).
- **Deploy:** V78 is one-way and not rolling-deploy-safe — stop old JAR → start new JAR (Flyway runs first); targeted `pg_restore -t person_relationships` for rollback. No maintenance window.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Marcel <marcel@familienarchiv>
Reviewed-on: #841

.specify/rtm.md

@@ -139,6 +139,25 @@
 | REQ-014 | no change to DTO order, density threshold (12), gap-folding, or ol/section/h2 structure | #833 | zeitstrahl-visual-fidelity | `frontend/src/lib/timeline/*` | existing timeline + `zeitstrahl/page.server.test.ts` suites stay green (142 tests) | Done |
 | REQ-015 | new user-facing strings are Paraglide keys present in de/en/es with matching key sets | #833 | zeitstrahl-visual-fidelity | `frontend/messages/{de,en,es}.json` | `messages.spec.ts#zeitstrahl visual-fidelity keys are present in all locales`, `#identical key sets` | Done |
 | REQ-016 | LetterCard with no title → no ✉, no sr-only "Brief"; sender→receiver + date still render | #833 | zeitstrahl-visual-fidelity | `frontend/src/lib/timeline/LetterCard.svelte` | `LetterCard.svelte.spec.ts#renders no ✉ glyph and no "Brief" label when the title is empty` | Done |
+| REQ-001 | store relationship from/to as nullable LocalDate + NOT-NULL DatePrecision (default UNKNOWN) | #837 | relationship-edit-dates | `person/relationship/PersonRelationship.java`, `V78__relationship_years_to_localdate.sql` | `RelationshipMigrationTest#yearColumnsDropped_andNamedCheckConstraintsExist`, `RelationshipServiceTest#addRelationship_persists_with_storage_truth` | Done |
+| REQ-002 | V78 backfills non-null years as `{year}-01-01`/YEAR, nulls → null/UNKNOWN, rows preserved | #837 | relationship-edit-dates | `V78__relationship_years_to_localdate.sql` | `RelationshipMigrationTest#backfill_fromYearAndToYear_becomeYearPrecisionDates`, `#backfill_bothNull_leavesDatesNullAndPrecisionsUnknown`, `#backfill_preservesRowCount` | Done |
+| REQ-003 | named DB CHECKs: coherence both ends + fromDate ≤ toDate | #837 | relationship-edit-dates | `V78__relationship_years_to_localdate.sql` | `RelationshipMigrationTest#orderCheckConstraint_rejectsToDateBeforeFromDate`, `#coherenceCheckConstraint_rejectsDatePresentWithUnknownPrecision` | Done |
+| REQ-004 | PUT updates the relationship → 200 RelationshipDTO | #837 | relationship-edit-dates | `person/relationship/RelationshipController#updateRelationship`, `RelationshipService#updateRelationship` | `RelationshipControllerTest#updateRelationship_returns200_with_RelationshipDTO_for_WRITE_ALL_user`, `RelationshipServiceIntegrationTest#updateRelationship_persists_new_type_dates_and_notes`, `page.server.spec.ts#updateRelationship PUTs to the relId path with the new body` | Done |
+| REQ-005 | create + update rejected with 403 without WRITE_ALL | #837 | relationship-edit-dates | `person/relationship/RelationshipController` (`@RequirePermission`) | `RelationshipControllerTest#updateRelationship_returns403_for_READ_ALL_only_user`, `#addRelationship_returns403_for_user_with_READ_ALL_only` | Done |
+| REQ-006 | relId not existing / not owned by person → 404 RELATIONSHIP_NOT_FOUND | #837 | relationship-edit-dates | `person/relationship/RelationshipService#loadOwnedRelationship` | `RelationshipServiceTest#updateRelationship_throws_NOT_FOUND_when_rel_belongs_to_different_person`, `RelationshipServiceIntegrationTest#updateRelationship_throws_404_when_rel_belongs_to_different_person` | Done |
+| REQ-007 | update with relatedPersonId == {id} → 400 VALIDATION_ERROR | #837 | relationship-edit-dates | `person/relationship/RelationshipService#updateRelationship` | `RelationshipServiceTest#updateRelationship_throws_VALIDATION_ERROR_on_self_relation` | Done |
+| REQ-008 | resulting (person, relatedPerson, type) duplicate → 409 DUPLICATE_RELATIONSHIP | #837 | relationship-edit-dates | `person/relationship/RelationshipService#updateRelationship` | `RelationshipServiceTest#updateRelationship_throws_DUPLICATE_when_db_constraint_violated` | Done |
+| REQ-009 | update to PARENT_OF with reverse PARENT_OF present → 409 CIRCULAR_RELATIONSHIP | #837 | relationship-edit-dates | `person/relationship/RelationshipService#updateRelationship` | `RelationshipServiceTest#updateRelationship_throws_CIRCULAR_when_reverse_PARENT_OF_exists` | Done |
+| REQ-010 | toDate before fromDate → 400 INVALID_RELATIONSHIP_DATES | #837 | relationship-edit-dates | `person/relationship/RelationshipService#validateRelationshipDates`, `exception/ErrorCode`, `frontend/src/lib/shared/errors.ts` | `RelationshipServiceTest#addRelationship_throws_INVALID_RELATIONSHIP_DATES_when_toDate_before_fromDate`, `#updateRelationship_throws_INVALID_RELATIONSHIP_DATES_when_toDate_before_fromDate` | Done |
+| REQ-011 | date+UNKNOWN precision, or precision without date → 400 INVALID_DATE_PRECISION | #837 | relationship-edit-dates | `person/relationship/RelationshipService#requireDatePrecisionCoherence` | `RelationshipServiceTest#addRelationship_throws_INVALID_DATE_PRECISION_when_date_present_but_precision_unknown`, `#addRelationship_throws_INVALID_DATE_PRECISION_when_precision_set_without_date` | Done |
+| REQ-012 | invalid enum / missing relatedPersonId·relationType / notes > 2000 → 400 VALIDATION_ERROR | #837 | relationship-edit-dates | `person/relationship/RelationshipUpsertRequest` (Bean Validation), `RelationshipController` | `RelationshipControllerTest#updateRelationship_returns400_when_relationType_is_unknown_value`, `#addRelationship_returns400_when_relationType_is_unknown_value` | Done |
+| REQ-013 | updating into a family type flags both endpoints (additive) | #837 | relationship-edit-dates | `person/relationship/RelationshipService#updateRelationship` | `RelationshipServiceTest#updateRelationship_marks_both_endpoints_family_when_updated_to_family_type` | Done |
+| REQ-014 | persist + display notes on create, update, read and edit views | #837 | relationship-edit-dates | `person/relationship/RelationshipService`, `frontend/.../AddRelationshipForm.svelte`, `routes/persons/[id]/PersonRelationshipsCard.svelte` | `RelationshipServiceIntegrationTest#updateRelationship_persists_new_type_dates_and_notes`, `AddRelationshipForm.svelte.spec.ts#round-trips the notes into the textarea`, `PersonRelationshipsCard.svelte.test.ts#shows the notes line` | Done |
+| REQ-015 | detail view shows the date range at its precision; no dates → no date line | #837 | relationship-edit-dates | `frontend/src/lib/person/relationshipDates.ts`, `routes/persons/[id]/PersonRelationshipsCard.svelte` | `relationshipDates.spec.ts`, `PersonRelationshipsCard.svelte.test.ts#renders the date range at its stored precision`, `#renders no date line when the relationship has no dates` | Done |
+| REQ-016 | edit affordance opens a form pre-filled with type/person/dates+precision/notes; precision DAY/MONTH/YEAR | #837 | relationship-edit-dates | `frontend/.../AddRelationshipForm.svelte`, `RelationshipDateField.svelte`, `RelationshipChip.svelte` | `AddRelationshipForm.svelte.spec.ts#pre-fills the from-date as dd.mm.yyyy`, `#offers only DAY/MONTH/YEAR in each precision select`, `RelationshipChip.svelte.spec.ts#shows an Edit affordance with an accessible name when canWrite and onEdit` | Done |
+| REQ-017 | derived Heirat sources SPOUSE_OF.fromDate + fromDatePrecision | #837 | relationship-edit-dates | `timeline/TimelineEventService#buildMarriageEvents` | `DerivedEventsAssemblyTest#should_emit_day_precision_heirat_from_spouse_fromDate` | Done |
+| REQ-018 | unauthenticated PUT → 401, no row modified | #837 | relationship-edit-dates | `person/relationship/RelationshipController` (SecurityConfig) | `RelationshipControllerTest#updateRelationship_returns401_whenUnauthenticated_and_does_not_touch_service` | Done |
+| REQ-019 | while a create/update request is in flight, submit is disabled + shows a progress indicator | #837 | relationship-edit-dates | `frontend/src/lib/person/relationship/AddRelationshipForm.svelte` | `AddRelationshipForm.svelte.spec.ts#disables the submit and shows a progress spinner while a submit is in flight` | Done |
 | REQ-001 | TimelineEntryDTO carries rootTagId/rootTagName/rootTagColor for LETTER entries, assembled in-transaction (id+name+token only) | #835 | zeitstrahl-tag-chips | `timeline/TimelineEntryDTO`, `timeline/TimelineService#mapDocument` | `TimelineServiceTest#letter_with_tags_carries_its_primary_root_tag` | Done |
 | REQ-002 | the three root-tag fields are nullable and not `@Schema(requiredMode = REQUIRED)` | #835 | zeitstrahl-tag-chips | `timeline/TimelineEntryDTO`, `frontend/src/lib/generated/api.ts` (optional) | `TimelineServiceTest#untagged_letter_has_no_root_tag_fields` (+ regenerated `api.ts` shows `rootTag*?`) | Done |
 | REQ-003 | primary tag = root ancestor of the alphabetically-first assigned tag, resolved via TagService | #835 | zeitstrahl-tag-chips | `tag/TagService#resolveRootTags`, `timeline/TimelineService#primaryTag` | `TimelineServiceTest#letter_with_tags_carries_its_primary_root_tag`, `TagServiceTest#resolveRootTags_walksChildToRoot_withRootColor`, `TagServiceIntegrationTest#resolveRootTags_walksPersistedChainToRoot_withRootColor` | Done |