test(person): pin fetchPool dedup when one person matches two tokens (#763 review)

Assert that when the same person id is returned by two different token
fetches, the person appears exactly once in the result -- pinning
fetchPool's putIfAbsent dedup so a future refactor can't silently
double-classify a candidate.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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

@@ -1045,4 +1045,18 @@ class PersonServiceTest {
 
         verify(personRepository, org.mockito.Mockito.atMost(8)).searchByName(any());
     }
+
+    @Test
+    void resolveByName_samePersonFromTwoTokens_appearsOnce() {
+        // Both token fetches return the same person id — fetchPool's putIfAbsent must dedup so the
+        // candidate is classified once, not twice.
+        Person clara = Person.builder().id(UUID.randomUUID()).firstName("Clara").lastName("Cram").build();
+        when(personRepository.searchByName("clara")).thenReturn(List.of(clara));
+        when(personRepository.searchByName("cram")).thenReturn(List.of(clara));
+
+        NameMatches result = personService.resolveByName("Clara Cram");
+
+        assertThat(result.direct()).hasSize(1);
+        assertThat(result.partial()).isEmpty();
+    }
 }