Replace person_relationships.from_year/to_year (Integer) with from_date/
to_date (LocalDate) + NOT-NULL from_date_precision/to_date_precision
(DatePrecision, default UNKNOWN), mirroring the Person life-date pattern
(ADR-039 / V76). V78 backfills existing years as YYYY-01-01 at YEAR precision,
adds five named CHECK constraints (coherence both ends, from<=to, precision
value sets) and drops the year columns — verified by RelationshipMigrationTest
on a real Postgres 16 container.
validateRelationshipDates replaces validateYears: coherence (date <=> non-
UNKNOWN precision) -> INVALID_DATE_PRECISION, order (toDate before fromDate) ->
INVALID_RELATIONSHIP_DATES. The derived Zeitstrahl Heirat event now sources the
SPOUSE_OF.from_date at its stored precision, so a DAY-precision wedding surfaces
the exact day instead of just the year. RelationshipDTO and the shared
create/update request (renamed CreateRelationshipRequest ->
RelationshipUpsertRequest) carry the date+precision fields.
REQ-001, REQ-002, REQ-003, REQ-010, REQ-011, REQ-014, REQ-017
Refs #837
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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