feat(backend): add received-documents endpoint for persons

Add findByReceiversId to DocumentRepository, getDocumentsByReceiver
to DocumentService, and GET /api/persons/{id}/received-documents
to PersonController. Tests added for both service and controller layers.

Closes #1
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/main/java/org/raddatz/familienarchiv/controller/PersonController.java

@@ -38,6 +38,11 @@ public class PersonController {
         return documentService.getDocumentsBySender(id);
     }
 
+    @GetMapping("/{id}/received-documents")
+    public List<Document> getPersonReceivedDocuments(@PathVariable UUID id) {
+        return documentService.getDocumentsByReceiver(id);
+    }
+
     @PostMapping
     public ResponseEntity<Person> createPerson(@RequestBody Map<String, String> body) {
         String firstName = body.get("firstName");

backend/src/main/java/org/raddatz/familienarchiv/repository/DocumentRepository.java

@@ -30,6 +30,8 @@ public interface DocumentRepository extends JpaRepository<Document, UUID>, JpaSp
 
     List<Document> findBySenderId(UUID senderId);
 
+    List<Document> findByReceiversId(UUID receiverId);
+
     List<Document> findByTags_Id(UUID tagId);
 
     @Query("SELECT DISTINCT d FROM Document d " +

backend/src/main/java/org/raddatz/familienarchiv/service/DocumentService.java

@@ -254,6 +254,10 @@ public class DocumentService {
         return documentRepository.findBySenderId(senderId);
     }
 
+    public List<Document> getDocumentsByReceiver(UUID receiverId) {
+        return documentRepository.findByReceiversId(receiverId);
+    }
+
     public List<Document> getConversationFiltered(UUID senderId, UUID receiverId, LocalDate from, LocalDate to, Sort sort) {
         LocalDate dateFrom = (from != null) ? from : LocalDate.parse("0000-01-01");
         LocalDate dateTo = (to != null) ? to : LocalDate.now();