fix(review): address PR #787 review blockers — db-orm diagram, C4 diagram, UUID link text

- db-orm.puml: replace geschichten_documents with journey_items, add type column to geschichten, bump schema version to V72
- l3-backend-3g-supporting.puml: update GeschichteController and GeschichteService descriptions to mention STORY/JOURNEY subtypes and JourneyItem
- geschichten/[id]/+page.svelte: replace raw UUID fallback with m.geschichten_document_link_placeholder() i18n key
- messages/{de,en,es}.json: add geschichten_document_link_placeholder translation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/architecture/db/db-orm.puml

@@ -1,6 +1,6 @@
 @startuml db-orm
-' Schema source: Flyway V1–V69 (excl. V37, V43 — intentionally removed)
-' Schema as of:  V69 (2026-05-27)
+' Schema source: Flyway V1–V72 (excl. V37, V43 — intentionally removed)
+' Schema as of:  V72 (2026-06-08)
 ' ⚠ This is a versioned snapshot. Update when the schema changes significantly.
 
 hide circle
@@ -359,6 +359,7 @@ package "Supporting" {
     title : VARCHAR(255) NOT NULL
     body : TEXT
     status : VARCHAR(32) NOT NULL
+    type : VARCHAR(32) NOT NULL
     author_id : UUID <<FK>>
     created_at : TIMESTAMP NOT NULL
     updated_at : TIMESTAMP NOT NULL
@@ -370,9 +371,13 @@ package "Supporting" {
     person_id : UUID <<FK>>
   }
 
-  entity geschichten_documents {
+  entity journey_items {
+    id : UUID <<PK>>
+    --
     geschichte_id : UUID <<FK>>
     document_id : UUID <<FK>>
+    position : INTEGER NOT NULL
+    note : TEXT
   }
 }
 
@@ -436,7 +441,7 @@ audit_log }o--o| documents : document_id
 geschichten }o--o| app_users : author_id
 geschichten_persons }o--|| geschichten : geschichte_id
 geschichten_persons }o--|| persons : person_id
-geschichten_documents }o--|| geschichten : geschichte_id
-geschichten_documents }o--|| documents : document_id
+journey_items }o--|| geschichten : geschichte_id (ON DELETE CASCADE)
+journey_items }o--o| documents : document_id (ON DELETE SET NULL)
 
 @enduml