refactor(document): compute hasTranscription only on the detail path (#697)

Move the hasTranscription existence query out of the shared getDocumentById
into a dedicated getDocumentDetail used solely by GET /api/documents/{id}.
The flag is only consumed by the detail page, so the extra EXISTS query no
longer runs for the many internal getDocumentById callers (e.g. the
Geschichte resolve loop and the dashboard resume path). Behaviour of the
detail endpoint is unchanged.

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

backend/src/main/java/org/raddatz/familienarchiv/document/DocumentController.java

@@ -138,7 +138,7 @@ public class DocumentController {
     // --- METADATA ---
     @GetMapping("/{id}")
     public Document getDocument(@PathVariable UUID id) {
-        return documentService.getDocumentById(id);
+        return documentService.getDocumentDetail(id);
     }
 
     @PostMapping(consumes = MediaType.MULTIPART_FORM_DATA_VALUE)

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

@@ -943,6 +943,18 @@ public class DocumentService {
         Document doc = documentRepository.findById(id)
                 .orElseThrow(() -> DomainException.notFound(ErrorCode.DOCUMENT_NOT_FOUND, "Document not found: " + id));
         tagService.resolveEffectiveColors(doc.getTags());
+        return doc;
+    }
+
+    /**
+     * Loads a document for the detail view, additionally flagging whether it has any
+     * transcription to read. Kept separate from {@link #getDocumentById} so the cheap
+     * existence query only runs for the single-document detail endpoint, not for the
+     * many internal callers that never read the flag.
+     */
+    @Transactional(readOnly = true)
+    public Document getDocumentDetail(UUID id) {
+        Document doc = getDocumentById(id);
         doc.setHasTranscription(transcriptionBlockQueryService.hasBlocks(id));
         return doc;
     }

backend/src/test/java/org/raddatz/familienarchiv/document/DocumentServiceTest.java

@@ -119,23 +119,34 @@ class DocumentServiceTest {
     }
 
     @Test
-    void getDocumentById_setsHasTranscriptionTrue_whenBlocksExist() {
+    void getDocumentById_doesNotQueryTranscription() {
+        UUID id = UUID.randomUUID();
+        Document doc = Document.builder().id(id).title("Test").build();
+        when(documentRepository.findById(id)).thenReturn(Optional.of(doc));
+
+        documentService.getDocumentById(id);
+
+        verifyNoInteractions(transcriptionBlockQueryService);
+    }
+
+    @Test
+    void getDocumentDetail_setsHasTranscriptionTrue_whenBlocksExist() {
         UUID id = UUID.randomUUID();
         Document doc = Document.builder().id(id).title("Test").build();
         when(documentRepository.findById(id)).thenReturn(Optional.of(doc));
         when(transcriptionBlockQueryService.hasBlocks(id)).thenReturn(true);
 
-        assertThat(documentService.getDocumentById(id).isHasTranscription()).isTrue();
+        assertThat(documentService.getDocumentDetail(id).isHasTranscription()).isTrue();
     }
 
     @Test
-    void getDocumentById_setsHasTranscriptionFalse_whenNoBlocksExist() {
+    void getDocumentDetail_setsHasTranscriptionFalse_whenNoBlocksExist() {
         UUID id = UUID.randomUUID();
         Document doc = Document.builder().id(id).title("Test").build();
         when(documentRepository.findById(id)).thenReturn(Optional.of(doc));
         when(transcriptionBlockQueryService.hasBlocks(id)).thenReturn(false);
 
-        assertThat(documentService.getDocumentById(id).isHasTranscription()).isFalse();
+        assertThat(documentService.getDocumentDetail(id).isHasTranscription()).isFalse();
     }
 
     // ─── updateDocument ───────────────────────────────────────────────────────