Add job tracking with PostgreSQL, image storage, and review workflow

- Add PostgreSQL service to docker-compose with health check and postgres_data volume
- Mount ./ocr_images as bind volume for persistent image storage
- Add backend/database.py with schema init and get_db() context manager
- Add 5 new API endpoints: POST /api/jobs, GET /api/jobs (search), GET /api/jobs/{id},
  GET /api/jobs/{id}/image, PUT /api/jobs/{id}/review
- Jobs are saved with author/book/chapter/page metadata, auto UUID, and submitted_at timestamp
- Jobs start as 'unreviewed'; review captures edited text, reviewer name, and reviewed_at
- Add MetadataForm.jsx (author/book/chapter/page inputs) to the New Job panel
- Add JobsPanel.jsx with search/filter, paginated list, and detail pane with review form
- Add "Commit Job" button to ResultPanel (plain_ocr mode only) with success/error feedback
- Add "New Job" / "Browse Jobs" navigation to the app header

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

docker-compose.yml

@@ -1,4 +1,19 @@
 services:
+  postgres:
+    image: postgres:16-alpine
+    container_name: deepseek-ocr-postgres
+    environment:
+      POSTGRES_USER: ${POSTGRES_USER:-ocr_user}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-ocr_password}
+      POSTGRES_DB: ${POSTGRES_DB:-ocr_db}
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER:-ocr_user} -d ${POSTGRES_DB:-ocr_db}"]
+      interval: 5s
+      timeout: 5s
+      retries: 10
+
   backend:
     build: ./backend
     container_name: deepseek-ocr-backend
@@ -10,8 +25,14 @@ services:
       API_HOST: ${API_HOST:-0.0.0.0}
       API_PORT: ${API_PORT:-8000}
       MAX_UPLOAD_SIZE_MB: ${MAX_UPLOAD_SIZE_MB:-100}
+      DATABASE_URL: ${DATABASE_URL:-postgresql://ocr_user:ocr_password@postgres:5432/ocr_db}
+      OCR_IMAGES_DIR: ${OCR_IMAGES_DIR:-/data/ocr_images}
     volumes:
       - ./models:/models
+      - ./ocr_images:/data/ocr_images
+    depends_on:
+      postgres:
+        condition: service_healthy
     deploy:
       resources:
         reservations:
@@ -22,8 +43,6 @@ services:
     shm_size: "4g"
     ports:
       - "${API_PORT:-8000}:${API_PORT:-8000}"
-    networks:
-      - ocr-network
 
   frontend:
     build: ./frontend
@@ -32,9 +51,10 @@ services:
       - "${FRONTEND_PORT:-3000}:80"
     depends_on:
       - backend
-    networks:
-      - ocr-network
+
+volumes:
+  postgres_data:
 
 networks:
-  ocr-network:
-    driver: bridge
+  default:
+    name: rw-research