docs(planning): generate codebase map via gsd-map-codebase

.planning/codebase/STACK.md

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+# STACK
+
+## Core Language & Environment
+- **Python**: Primary language for all scripts (v3.10+ expected).
+
+## Principal Libraries
+- **OpenCV (`cv2`)**: Core computer vision operations, image thresholding, morphological operations, pattern matching (Template Matching), Difference Hash (`_dhash`), Laplacian variance.
+- **NumPy (`np`)**: Matrix operations and mask manipulations for image arrays.
+- **EasyOCR (`easyocr`)**: Convolutional/Recurrent Neural Network based OCR for detecting measure numbers to prevent duplications.
+
+## Utilities
+- **yt-dlp**: Command-line tool called via `subprocess` for downloading high-quality video frames (720p preferred over 1080p to optimize processing) from YouTube.
+- **img2pdf**: Lightweight library to convert combined tab images into A4 PDF output.
+- **Pillow (`PIL`)**: Additional image manipulation where OpenCV is less ergonomic.
+
+## Execution Requirements
+- Windows OS (noted via `sys.platform == "win32"` encodings).