feat: MCP toolsets in WebUI + onboarding fix for non-standard providers — v0.50.63

Squash-merges PR #578 (rebased from #574 by @renheqiang + #575 by @nesquena-hermes). MCP server toolsets now included in WebUI sessions; onboarding wizard no longer fires for non-standard providers. 1331 tests pass. Nathan override applied for self-built #575.

api/routes.py

@@ -29,7 +29,7 @@ from api.config import (
     STREAMS_LOCK,
     CANCEL_FLAGS,
     SERVER_START_TIME,
-    CLI_TOOLSETS,
+    _resolve_cli_toolsets,
     _INDEX_HTML_PATH,
     get_available_models,
     IMAGE_EXTS,
@@ -2070,7 +2070,7 @@ def _handle_chat_sync(handler, body):
                 api_key=_api_key,
                 platform="cli",
                 quiet_mode=True,
-                enabled_toolsets=CLI_TOOLSETS,
+                enabled_toolsets=_resolve_cli_toolsets(),
                 session_id=s.session_id,
             )
             workspace_ctx = f"[Workspace: {s.workspace}]\n"