fix: update MiniMax/Z.AI model lists, pass base_url to AIAgent

- Update _PROVIDER_MODELS['minimax'] from stale ABAB 6.5 models to
  current MiniMax-M2.7/M2.5/M2.1 lineup (matching hermes-agent upstream)
- Update _PROVIDER_MODELS['zai'] from GLM-4 to current GLM-5/4.7/4.5
  lineup (matching hermes-agent upstream)
- Extend resolve_model_provider() to also return base_url from config.yaml,
  so providers with custom endpoints (MiniMax, Z.AI) are routed correctly
- Pass base_url to AIAgent in both streaming and sync chat paths

Fixes #6

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

api/routes.py

@@ -630,8 +630,9 @@ def _handle_chat_sync(handler, body):
         from run_agent import AIAgent
         with CHAT_LOCK:
             from api.config import resolve_model_provider
-            _model, _provider = resolve_model_provider(s.model)
-            agent = AIAgent(model=_model, provider=_provider, platform='cli', quiet_mode=True,
+            _model, _provider, _base_url = resolve_model_provider(s.model)
+            agent = AIAgent(model=_model, provider=_provider, base_url=_base_url,
+                           platform='cli', quiet_mode=True,
                            enabled_toolsets=CLI_TOOLSETS, session_id=s.session_id)
             workspace_ctx = f"[Workspace: {s.workspace}]\n"
             workspace_system_msg = (