feat: add core OCR API integration (refs #65)

OCR Service (Python/FastAPI):
- POST /extract for synchronous OCR extraction
- POST /jobs and GET /jobs/{job_id} for async processing
- Image preprocessing (deskew, denoise) for accuracy
- HEIC conversion via pillow-heif
- Redis job queue for async processing

Backend (Fastify):
- POST /api/ocr/extract - authenticated proxy to OCR
- POST /api/ocr/jobs - async job submission
- GET /api/ocr/jobs/:jobId - job polling
- Multipart file upload handling
- JWT authentication required

File size limits: 10MB sync, 200MB async
Processing time target: <3 seconds for typical photos

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ocr/app/routers/extract.py

@@ -0,0 +1,69 @@
+"""OCR extraction endpoints."""
+import logging
+
+from fastapi import APIRouter, File, HTTPException, Query, UploadFile
+
+from app.models import OcrResponse
+from app.services import ocr_service
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/extract", tags=["extract"])
+
+# Maximum file size for synchronous processing (10MB)
+MAX_SYNC_SIZE = 10 * 1024 * 1024
+
+
+@router.post("", response_model=OcrResponse)
+async def extract_text(
+    file: UploadFile = File(..., description="Image file to process"),
+    preprocess: bool = Query(True, description="Apply image preprocessing"),
+) -> OcrResponse:
+    """
+    Extract text from an uploaded image using OCR.
+
+    Supports HEIC, JPEG, PNG, and PDF (first page only) formats.
+    Processing time target: <3 seconds for typical photos.
+
+    - **file**: Image file (max 10MB for sync processing)
+    - **preprocess**: Whether to apply deskew/denoise preprocessing (default: true)
+    """
+    # Validate file presence
+    if not file.filename:
+        raise HTTPException(status_code=400, detail="No file provided")
+
+    # Read file content
+    content = await file.read()
+    file_size = len(content)
+
+    # Validate file size
+    if file_size > MAX_SYNC_SIZE:
+        raise HTTPException(
+            status_code=413,
+            detail=f"File too large for sync processing. Max: {MAX_SYNC_SIZE // (1024*1024)}MB. Use /jobs for larger files.",
+        )
+
+    if file_size == 0:
+        raise HTTPException(status_code=400, detail="Empty file provided")
+
+    logger.info(
+        f"Processing file: {file.filename}, "
+        f"size: {file_size} bytes, "
+        f"content_type: {file.content_type}"
+    )
+
+    # Perform OCR extraction
+    result = ocr_service.extract(
+        file_bytes=content,
+        content_type=file.content_type,
+        preprocess=preprocess,
+    )
+
+    if not result.success:
+        logger.warning(f"OCR extraction failed for {file.filename}")
+        raise HTTPException(
+            status_code=422,
+            detail="Failed to extract text from image. Ensure the file is a valid image format.",
+        )
+
+    return result