refactor: keep only model discovery, drop redundant routing changes

- Revert routes.py and streaming.py to master: resolve_model_provider()
  already handles provider routing and base_url passthrough for all models.
- Fix indentation error in config.py (2-space indent on comment line).
- Fix auto_detected_models scope: initialize before try block.
- Remove unused urllib.parse import.
- Simplify unknown-provider model group logic.
- Remove verbose comments and redundant variable assignments.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/streaming.py

@@ -32,7 +32,7 @@ def _sse(handler, event, data):
     handler.wfile.flush()
 
 
-def _run_agent_streaming(session_id, msg_text, model, workspace, stream_id, attachments=None, base_url=None, provider=None):
+def _run_agent_streaming(session_id, msg_text, model, workspace, stream_id, attachments=None):
     """Run agent in background thread, writing SSE events to STREAMS[stream_id]."""
     q = STREAMS.get(stream_id)
     if q is None: