feat(transcription): add source/reviewed fields for training pipeline

- BlockSource enum: MANUAL, OCR
- V26 migration adds source + reviewed columns to transcription_blocks
- OcrService sets source=OCR when creating blocks
- TranscriptionService.reviewBlock() toggles the reviewed flag
- PUT /api/documents/{id}/transcription-blocks/{blockId}/review endpoint
- 5 new tests: reviewBlock toggle/untoggle/notfound, controller,
  OcrService source=OCR verification

The reviewed flag enables the Kraken fine-tuning pipeline: only blocks
marked as reviewed by a human are exported as training data.

Refs #226

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

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

@@ -81,6 +81,14 @@ public class TranscriptionBlockController {
         return transcriptionService.listBlocks(documentId);
     }
 
+    @PutMapping("/{blockId}/review")
+    @RequirePermission(Permission.WRITE_ALL)
+    public TranscriptionBlock reviewBlock(
+            @PathVariable UUID documentId,
+            @PathVariable UUID blockId) {
+        return transcriptionService.reviewBlock(documentId, blockId);
+    }
+
     @GetMapping("/{blockId}/history")
     @RequirePermission(Permission.READ_ALL)
     public List<TranscriptionBlockVersion> getBlockHistory(

backend/src/main/java/org/raddatz/familienarchiv/model/BlockSource.java

@@ -0,0 +1,6 @@
+package org.raddatz.familienarchiv.model;
+
+public enum BlockSource {
+    MANUAL,
+    OCR
+}

backend/src/main/java/org/raddatz/familienarchiv/model/TranscriptionBlock.java

@@ -41,6 +41,17 @@ public class TranscriptionBlock {
     @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
     private int sortOrder;
 
+    @Enumerated(EnumType.STRING)
+    @Column(nullable = false, length = 10)
+    @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+    @Builder.Default
+    private BlockSource source = BlockSource.MANUAL;
+
+    @Column(nullable = false)
+    @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+    @Builder.Default
+    private boolean reviewed = false;
+
     @Version
     @Column(nullable = false)
     @Schema(requiredMode = Schema.RequiredMode.REQUIRED)

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

@@ -107,6 +107,7 @@ public class OcrService {
                     .documentId(documentId)
                     .text(block.text() != null ? block.text() : "")
                     .sortOrder(i)
+                    .source(BlockSource.OCR)
                     .createdBy(userId)
                     .updatedBy(userId)
                     .build();

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

@@ -116,6 +116,13 @@ public class TranscriptionService {
         }
     }
 
+    @Transactional
+    public TranscriptionBlock reviewBlock(UUID documentId, UUID blockId) {
+        TranscriptionBlock block = getBlock(documentId, blockId);
+        block.setReviewed(!block.isReviewed());
+        return blockRepository.save(block);
+    }
+
     public List<TranscriptionBlockVersion> getBlockHistory(UUID documentId, UUID blockId) {
         getBlock(documentId, blockId);
         return versionRepository.findByBlockIdOrderByChangedAtDesc(blockId);

backend/src/main/resources/db/migration/V26__add_source_and_reviewed_to_transcription_blocks.sql

@@ -0,0 +1,2 @@
+ALTER TABLE transcription_blocks ADD COLUMN source VARCHAR(10) NOT NULL DEFAULT 'MANUAL';
+ALTER TABLE transcription_blocks ADD COLUMN reviewed BOOLEAN NOT NULL DEFAULT FALSE;