feat(geschichte): carry updatedAt in GeschichteSummary projection

The reader dashboard renders 'bearbeitet vor X' from updatedAt, but the
summary projection dropped the field when the list endpoint moved off the
entity — drafts have no publishedAt to fall back on.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/src/main/java/org/raddatz/familienarchiv/geschichte/GeschichteRepository.java

@@ -25,7 +25,7 @@ public interface GeschichteRepository extends JpaRepository<Geschichte, UUID>, J
      */
     @Query("""
             SELECT g.id AS id, g.title AS title, g.status AS status, g.type AS type,
-                   g.author AS author, g.publishedAt AS publishedAt, g.body AS body
+                   g.author AS author, g.publishedAt AS publishedAt, g.updatedAt AS updatedAt, g.body AS body
             FROM Geschichte g
             WHERE g.status = :effectiveStatus
               AND (:authorId IS NULL OR g.author.id = :authorId)

backend/src/main/java/org/raddatz/familienarchiv/geschichte/GeschichteSummary.java

@@ -31,6 +31,10 @@ public interface GeschichteSummary {
 
     LocalDateTime getPublishedAt();
 
+    /** Always set (@UpdateTimestamp) — drives "bearbeitet vor X" on dashboard cards. */
+    @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+    LocalDateTime getUpdatedAt();
+
     String getBody();
 
     interface AuthorSummary {

backend/src/test/java/org/raddatz/familienarchiv/geschichte/GeschichteControllerTest.java

@@ -401,6 +401,7 @@ class GeschichteControllerTest {
             public GeschichteType getType() { return GeschichteType.STORY; }
             public AuthorSummary getAuthor() { return null; }
             public LocalDateTime getPublishedAt() { return LocalDateTime.now(); }
+            public LocalDateTime getUpdatedAt() { return LocalDateTime.now(); }
             public String getBody() { return null; }
         };
     }

backend/src/test/java/org/raddatz/familienarchiv/geschichte/GeschichteListProjectionTest.java

@@ -61,6 +61,19 @@ class GeschichteListProjectionTest {
         assertThat(result.get(0).getTitle()).isEqualTo("Veröffentlicht");
     }
 
+    @Test
+    void findSummaries_carries_updatedAt_for_dashboard_relative_times() {
+        // ReaderDraftsModule renders "bearbeitet vor X" from updatedAt — the
+        // projection must carry it for drafts, where publishedAt is null.
+        geschichteRepository.save(draft("Mein Entwurf", author));
+
+        List<GeschichteSummary> result = geschichteRepository.findSummaries(
+                GeschichteStatus.DRAFT, author.getId(), sentinel(), 0, null);
+
+        assertThat(result).hasSize(1);
+        assertThat(result.get(0).getUpdatedAt()).isNotNull();
+    }
+
     @Test
     void findSummaries_returns_empty_list_when_no_published_geschichten_exist() {
         geschichteRepository.save(draft("Nur Entwurf", author));