fix(ocr): resume polling on page reload + track single-doc job status

Single-document OCR now creates an OcrJobDocument row so
GET /api/documents/{id}/ocr-status can find running jobs.
OcrAsyncRunner updates the job document status (RUNNING → DONE/FAILED).

Frontend checks OCR status when entering transcription mode —
if a job is running, resumes polling and shows the spinner.

Refs #226

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

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

@@ -39,16 +39,32 @@ public class OcrAsyncRunner {
         job.setStatus(OcrJobStatus.RUNNING);
         ocrJobRepository.save(job);
 
+        OcrJobDocument jobDoc = ocrJobDocumentRepository.findByJobIdAndDocumentId(jobId, documentId)
+                .orElse(null);
+        if (jobDoc != null) {
+            jobDoc.setStatus(OcrDocumentStatus.RUNNING);
+            ocrJobDocumentRepository.save(jobDoc);
+        }
+
         Document doc = documentService.getDocumentById(documentId);
 
         try {
             processDocument(documentId, doc, userId);
             job.setStatus(OcrJobStatus.DONE);
             job.setProcessedDocuments(1);
+            if (jobDoc != null) {
+                jobDoc.setStatus(OcrDocumentStatus.DONE);
+                ocrJobDocumentRepository.save(jobDoc);
+            }
         } catch (Exception e) {
             log.error("OCR processing failed for document {}", documentId, e);
             job.setStatus(OcrJobStatus.FAILED);
             job.setErrorCount(1);
+            if (jobDoc != null) {
+                jobDoc.setStatus(OcrDocumentStatus.FAILED);
+                jobDoc.setErrorMessage(e.getMessage());
+                ocrJobDocumentRepository.save(jobDoc);
+            }
         }
 
         ocrJobRepository.save(job);

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

@@ -5,6 +5,7 @@ import lombok.extern.slf4j.Slf4j;
 import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.exception.ErrorCode;
 import org.raddatz.familienarchiv.model.*;
+import org.raddatz.familienarchiv.repository.OcrJobDocumentRepository;
 import org.raddatz.familienarchiv.repository.OcrJobRepository;
 import org.springframework.stereotype.Service;
 
@@ -18,6 +19,7 @@ public class OcrService {
     private final OcrHealthClient ocrHealthClient;
     private final DocumentService documentService;
     private final OcrJobRepository ocrJobRepository;
+    private final OcrJobDocumentRepository ocrJobDocumentRepository;
     private final OcrAsyncRunner ocrAsyncRunner;
 
     public UUID startOcr(UUID documentId, ScriptType scriptTypeOverride, UUID userId) {
@@ -44,6 +46,13 @@ public class OcrService {
                 .build();
         job = ocrJobRepository.save(job);
 
+        OcrJobDocument jobDoc = OcrJobDocument.builder()
+                .jobId(job.getId())
+                .documentId(documentId)
+                .status(OcrDocumentStatus.PENDING)
+                .build();
+        ocrJobDocumentRepository.save(jobDoc);
+
         ocrAsyncRunner.runSingleDocument(job.getId(), documentId, userId);
         return job.getId();
     }

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

@@ -8,6 +8,7 @@ import org.mockito.junit.jupiter.MockitoExtension;
 import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.exception.ErrorCode;
 import org.raddatz.familienarchiv.model.*;
+import org.raddatz.familienarchiv.repository.OcrJobDocumentRepository;
 import org.raddatz.familienarchiv.repository.OcrJobRepository;
 
 import java.util.UUID;
@@ -24,6 +25,7 @@ class OcrServiceTest {
     @Mock OcrHealthClient ocrHealthClient;
     @Mock DocumentService documentService;
     @Mock OcrJobRepository ocrJobRepository;
+    @Mock OcrJobDocumentRepository ocrJobDocumentRepository;
     @Mock OcrAsyncRunner ocrAsyncRunner;
 
     @InjectMocks OcrService ocrService;