Restructure repo: add Python EMG scripts and move ESP32 code to EMG_Arm/

- Add emg_gui.py, learning_data_collection.py, learning_emg_filtering.py
- Add collected EMG data and trained models
- Move ESP32/PlatformIO code into EMG_Arm/ subdirectory
- Add servo control functions for robotic hand (flex/unflex fingers)
- Update .gitignore for Python and PlatformIO
- Exclude large asset files from repo (>100MB)

.gitignore

@@ -1,5 +1,18 @@
-.pio
-.vscode/.browse.c_cpp.db*
-.vscode/c_cpp_properties.json
-.vscode/launch.json
-.vscode/ipch
+# Python
+__pycache__/
+*.py[cod]
+*.egg-info/
+.venv/
+venv/
+
+# PlatformIO
+EMG_Arm/.pio/
+EMG_Arm/.vscode/
+
+# Data (uncomment if you want to exclude)
+# collected_data/
+# models/
+
+# OS
+.DS_Store
+Thumbs.db