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/instr/__init__.pyi

@@ -0,0 +1,24 @@
+__all__: list[str] = []
+
+# Enumerations
+TYPE_GENERAL: int
+TYPE_MARKER: int
+TYPE_WRAPPER: int
+TYPE_FUN: int
+TYPE = int
+"""One of [TYPE_GENERAL, TYPE_MARKER, TYPE_WRAPPER, TYPE_FUN]"""
+
+IMPL_PLAIN: int
+IMPL_IPP: int
+IMPL_OPENCL: int
+IMPL = int
+"""One of [IMPL_PLAIN, IMPL_IPP, IMPL_OPENCL]"""
+
+FLAGS_NONE: int
+FLAGS_MAPPING: int
+FLAGS_EXPAND_SAME_NAMES: int
+FLAGS = int
+"""One of [FLAGS_NONE, FLAGS_MAPPING, FLAGS_EXPAND_SAME_NAMES]"""
+
+
+