Refactor backend configuration management and update environment settings

- Replace the `config.py` module with a new `settings.py` to streamline environment variable management, focusing on database, CORS, and TURN settings.
- Update references throughout the backend codebase to use the new `settings` module instead of the deprecated `config`.
- Modify the `.env.example` file to reflect the new configuration approach, indicating that model provider credentials should be maintained separately.
- Enhance the `AssistantConfig` model to clarify the source of runtime connection information, ensuring it is injected from model resources rather than relying on defaults from the environment.
- Introduce new user scripts for audio and video management in the Tampermonkey environment, enhancing WebRTC capabilities.

backend/db/session.py

@@ -8,7 +8,7 @@
 from collections.abc import AsyncGenerator
 import json
 
-import config
+import settings
 from services.interface_catalog import INTERFACE_DEFINITIONS
 from sqlalchemy import text
 from sqlalchemy.ext.asyncio import (
@@ -17,7 +17,7 @@ from sqlalchemy.ext.asyncio import (
     create_async_engine,
 )
 
-engine = create_async_engine(config.DATABASE_URL, echo=False, pool_pre_ping=True)
+engine = create_async_engine(settings.DATABASE_URL, echo=False, pool_pre_ping=True)
 SessionLocal = async_sessionmaker(engine, expire_on_commit=False)