Reorganize project structure

- Move development and test files to dev/ directory
- Update .gitignore to exclude development files
- Update paths in configuration files
- Add new audio-player.js for frontend

.gitignore

@@ -48,6 +48,18 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 
+# Development directory
+dev/
+
+# Configuration files
+alembic.ini
+*.ini
+*.conf
+*.config
+*.yaml
+*.yml
+*.toml
+
 # IDEs and editors
 .vscode/
 .idea/