Add main application structure and logging configuration

- Implement main application entry point in duck-ocr.py
- Create logging configuration in logging_config.py
- Add video streaming functionality in camera.py
- Introduce main window UI in main_window.py
- Include SVG assets for UI buttons and icons
- Update .gitignore to exclude log files
- Add placeholder .gitkeep files for empty directories

assets/record_btn_off.svg

@@ -0,0 +1,12 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     width="24"
+     height="24">
+
+    <circle
+        cx="12"
+        cy="12"
+        r="9"
+        stroke="white"
+        stroke-width="2"
+        fill="none" />
+</svg>