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/numpy/_globals.pyi

@@ -0,0 +1,17 @@
+__all__ = ["_CopyMode", "_NoValue"]
+
+import enum
+from typing import Final, final
+
+@final
+class _CopyMode(enum.Enum):
+    ALWAYS = True
+    NEVER = False
+    IF_NEEDED = 2
+
+    def __bool__(self, /) -> bool: ...
+
+@final
+class _NoValueType: ...
+
+_NoValue: Final[_NoValueType] = ...