feat(phase1): implement OpenCV image processing pipeline

- Create ImageProcessor service with EXIF orientation detection
- Implement smart cropping via OpenCV contour detection (10% padding)
- Add text orientation detection using Hough line transform
- Resize and compress images to 1200px with 85% JPEG quality
- Generate 200px square thumbnails with center crop
- Fallback to Pillow if OpenCV fails
- Comprehensive test suite: 28 tests all passing
- File size validation (reject >10MB)
- Graceful error handling for corrupted/invalid images
- Update requirements.txt with opencv-python, piexif, python-magic

venv/lib/python3.12/site-packages/cv2/gapi/render/__init__.pyi

@@ -0,0 +1,5 @@
+__all__: list[str] = []
+
+from cv2.gapi.render import ocv as ocv
+
+

venv/lib/python3.12/site-packages/cv2/gapi/render/ocv/__init__.pyi

@@ -0,0 +1,9 @@
+__all__: list[str] = []
+
+import cv2
+
+
+# Functions
+def kernels() -> cv2.GKernelPackage: ...
+
+