test(person): alias-only and notes-only updates do not publish display-name event

Two regression guards on the "iff different" semantics in updatePerson.
Person.alias and Person.notes are not part of getDisplayName() — they live
outside DisplayNameFormatter — so changing only those fields must not fire
PersonDisplayNameChangedEvent. If a future refactor accidentally pulls
either field into the display name (or trips the comparison), these tests
catch it before transcription blocks get rewritten with stale "@OldAlias"
text.

Refs #362

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/src/test/java/org/raddatz/familienarchiv/service/PersonServiceTest.java

@@ -277,6 +277,46 @@ class PersonServiceTest {
                 .contains("Frau");
     }
 
+    @Test
+    void updatePerson_doesNotPublishEvent_whenOnlyAliasChanges() {
+        UUID id = UUID.randomUUID();
+        Person existing = Person.builder()
+                .id(id).firstName("Auguste").lastName("Raddatz")
+                .personType(PersonType.PERSON).alias("old alias").build();
+
+        when(personRepository.findById(id)).thenReturn(Optional.of(existing));
+        when(personRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+
+        PersonUpdateDTO dto = new PersonUpdateDTO();
+        dto.setPersonType(PersonType.PERSON);
+        dto.setFirstName("Auguste"); dto.setLastName("Raddatz");
+        dto.setAlias("new alias");
+
+        personService.updatePerson(id, dto);
+
+        verify(eventPublisher, never()).publishEvent(any(PersonDisplayNameChangedEvent.class));
+    }
+
+    @Test
+    void updatePerson_doesNotPublishEvent_whenOnlyNotesChanges() {
+        UUID id = UUID.randomUUID();
+        Person existing = Person.builder()
+                .id(id).firstName("Auguste").lastName("Raddatz")
+                .personType(PersonType.PERSON).notes("first note").build();
+
+        when(personRepository.findById(id)).thenReturn(Optional.of(existing));
+        when(personRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+
+        PersonUpdateDTO dto = new PersonUpdateDTO();
+        dto.setPersonType(PersonType.PERSON);
+        dto.setFirstName("Auguste"); dto.setLastName("Raddatz");
+        dto.setNotes("revised note");
+
+        personService.updatePerson(id, dto);
+
+        verify(eventPublisher, never()).publishEvent(any(PersonDisplayNameChangedEvent.class));
+    }
+
     // ─── findOrCreateByAlias ─────────────────────────────────────────────────
 
     @Test