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/services/webrtc_ice.py

@@ -7,28 +7,28 @@ import hashlib
 import hmac
 import time
 
-import config
+import settings
 
 STUN_URL = "stun:stun.l.google.com:19302"
 
 
 def _turn_credentials() -> tuple[str, str] | None:
     """Return (username, credential) for TURN, or None when TURN is not configured."""
-    if not config.TURN_URLS:
+    if not settings.TURN_URLS:
         return None
-    if config.TURN_SECRET:
-        expiry = int(time.time()) + config.TURN_CREDENTIAL_TTL
+    if settings.TURN_SECRET:
+        expiry = int(time.time()) + settings.TURN_CREDENTIAL_TTL
         username = f"{expiry}:ai-video"
         credential = base64.b64encode(
             hmac.new(
-                config.TURN_SECRET.encode("utf-8"),
+                settings.TURN_SECRET.encode("utf-8"),
                 username.encode("utf-8"),
                 hashlib.sha1,
             ).digest()
         ).decode("utf-8")
         return username, credential
-    if config.TURN_USERNAME and config.TURN_PASSWORD:
-        return config.TURN_USERNAME, config.TURN_PASSWORD
+    if settings.TURN_USERNAME and settings.TURN_PASSWORD:
+        return settings.TURN_USERNAME, settings.TURN_PASSWORD
     return None
 
 
@@ -39,7 +39,7 @@ def client_ice_servers() -> list[dict]:
     if not creds:
         return servers
     username, credential = creds
-    for url in config.TURN_URLS:
+    for url in settings.TURN_URLS:
         servers.append({"urls": url, "username": username, "credential": credential})
     return servers
 
@@ -53,7 +53,7 @@ def aiortc_ice_servers() -> list:
     if not creds:
         return servers
     username, credential = creds
-    for url in config.TURN_URLS:
+    for url in settings.TURN_URLS:
         servers.append(
             RTCIceServer(urls=url, username=username, credential=credential)
         )