🔌 feat: MCP OAuth Integration in Chat UI

- **Real-Time Connection Status**: New backend APIs and React Query hooks provide live MCP server connection monitoring with automatic UI updates
- **OAuth Flow Components**: Complete MCPConfigDialog, ServerInitializationSection, and CustomUserVarsSection with OAuth URL handling and polling-based completion
- **Enhanced Server Selection**: MCPSelect component with connection-aware filtering, visual status indicators, and better credential management UX

(still needs a lot of refinement since there is bloat/unused vars and functions leftover from the ideation phase on how to approach OAuth and connection statuses)

api/server/routes/config.js

@@ -106,6 +106,7 @@ router.get('/', async function (req, res) {
         const serverConfig = config.mcpServers[serverName];
         payload.mcpServers[serverName] = {
           customUserVars: serverConfig?.customUserVars || {},
+          requiresOAuth: req.app.locals.mcpOAuthRequirements?.[serverName] || false,
         };
       }
     }