fix: add back client logic for handling mcp.json

[ajshedivy]

Looks like #499 reverted some logic in useAppState hook in use-app-state.ts for handling mcp.json cli connection logic from #490.

This pull request updates the logic for auto-connecting to mcp.json provided MCP servers in the useAppState hook. Added code back that fetches the mcp configuration from an API endpoint instead of relying on a global window variable, supports multiple servers, and improves handling for auto-connect scenarios. The main changes are grouped below:

MCP Configuration Loading and Processing:

• Replaces the use of the global window.MCP_CLI_CONFIG with a fetch call to /api/mcp-cli-config to retrieve the mcp configuration, making it compatible with both development and production environments.
• Adds support for processing multiple servers from the mcp config, including logic to add each server to the UI and selectively auto-connect based on a filter (autoConnectServer).
• Improves handling for legacy single-server CLI config mode, maintaining backward compatibility.

Robustness and Logging Enhancements:

• Introduces a guard (cliConfigProcessedRef) to ensure the mcp config is processed only once per mount, preventing duplicate connections.
• Expands logging to provide more detailed information about server processing, connection attempts, and error handling during config fetch.

[chelojimenez]

lgtm! please run npm prettier-fix before merging

[chelojimenez]

tested with:
npm run build && npm start -- --config ../config.json

[chelojimenez]

created a PR so we update or docs to let devs know about this. we starting an open source repo for community mantained docs at https://docs.mcpjam.com/ if you wanna check it out!

[chelojimenez]

branch was failing bc our gh check was using a different node version, so i merged this!