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

run_migrations.py

@@ -18,7 +18,7 @@ def run_migrations():
     
     # Set up Alembic config
     alembic_cfg = Config()
-    alembic_cfg.set_main_option("script_location", "migrations")
+    alembic_cfg.set_main_option("script_location", "dev/migrations")
     alembic_cfg.set_main_option("sqlalchemy.url", database_url)
     
     # Run migrations