fix(geschichte): persist GeschichteType on create — JOURNEY was silently dropped

GeschichteUpdateDTO lacked a `type` field, so the `type: 'JOURNEY'` sent by
JourneyCreate was discarded by Jackson and every new Geschichte was saved as
STORY. The edit page branched on type, so journeys always showed the STORY
editor with no document-adding capability.

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

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

@@ -134,6 +134,7 @@ public class GeschichteService {
                 .title(dto.getTitle().trim())
                 .body(sanitize(dto.getBody()))
                 .status(GeschichteStatus.DRAFT)
+                .type(dto.getType() != null ? dto.getType() : GeschichteType.STORY)
                 .author(currentUser())
                 .persons(resolvePersons(dto.getPersonIds()))
                 .build();

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

@@ -15,5 +15,6 @@ public class GeschichteUpdateDTO {
     private String title;
     private String body;
     private GeschichteStatus status;
+    private GeschichteType type;
     private List<UUID> personIds;
 }

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

@@ -389,6 +389,37 @@ class GeschichteServiceTest {
                 .isEqualTo(ErrorCode.VALIDATION_ERROR);
     }
 
+    @Test
+    void create_preserves_JOURNEY_type_from_dto() {
+        authenticateAs(writer, Permission.BLOG_WRITE);
+        when(userService.findByEmail(writer.getEmail())).thenReturn(writer);
+        when(geschichteRepository.save(any(Geschichte.class)))
+                .thenAnswer(inv -> inv.getArgument(0));
+
+        GeschichteUpdateDTO dto = new GeschichteUpdateDTO();
+        dto.setTitle("My Journey");
+        dto.setType(GeschichteType.JOURNEY);
+
+        Geschichte saved = geschichteService.create(dto);
+
+        assertThat(saved.getType()).isEqualTo(GeschichteType.JOURNEY);
+    }
+
+    @Test
+    void create_defaults_to_STORY_when_type_is_null() {
+        authenticateAs(writer, Permission.BLOG_WRITE);
+        when(userService.findByEmail(writer.getEmail())).thenReturn(writer);
+        when(geschichteRepository.save(any(Geschichte.class)))
+                .thenAnswer(inv -> inv.getArgument(0));
+
+        GeschichteUpdateDTO dto = new GeschichteUpdateDTO();
+        dto.setTitle("My Story");
+
+        Geschichte saved = geschichteService.create(dto);
+
+        assertThat(saved.getType()).isEqualTo(GeschichteType.STORY);
+    }
+
     // ─── update ──────────────────────────────────────────────────────────────
 
     @Test