fix(provider): sync providers_config after creating new provider (#6388)

Fixes #6283

When adding a new embedding provider, the knowledge base creation page
did not show the new provider until restart.

Root cause: create_provider() did not update self.providers_config,
which is used by get_provider_config_list() to return provider lists.

This fix syncs the in-memory config after loading the new provider,
consistent with how reload() handles config updates.

Co-authored-by: ccsang <ccsang@users.noreply.github.com>

astrbot/core/provider/manager.py

@@ -808,6 +808,8 @@ class ProviderManager:
             config.save_config()
             # load instance
             await self.load_provider(new_config)
+            # sync in-memory config for API queries (e.g., embedding provider list)
+            self.providers_config = astrbot_config["provider"]
 
     async def terminate(self) -> None:
         if self._mcp_init_task and not self._mcp_init_task.done():