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/models/__init__.py

@@ -0,0 +1,18 @@
+"""Pydantic models for OCR service."""
+from .schemas import (
+    DocumentType,
+    ExtractedField,
+    JobResponse,
+    JobStatus,
+    JobSubmitRequest,
+    OcrResponse,
+)
+
+__all__ = [
+    "DocumentType",
+    "ExtractedField",
+    "JobResponse",
+    "JobStatus",
+    "JobSubmitRequest",
+    "OcrResponse",
+]