fix: add registeredTools count to health endpoint

Frontend expects health.registeredTools to display MCP Tools count.
Added mcpRegistry.getRegisteredTools().length to health response.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/backend/src/index.ts

@@ -136,12 +136,13 @@ async function startServer() {
 
     // Health check endpoint - FAST response
     app.get('/health', async (req, res) => {
-      // Basic process health
+      // Basic process health - registeredTools count fetched dynamically
       res.json({
         status: 'healthy', // Always return healthy if process is up
         timestamp: new Date().toISOString(),
         uptime: process.uptime(),
-        environment: process.env.NODE_ENV
+        environment: process.env.NODE_ENV,
+        registeredTools: mcpRegistry.getRegisteredTools().length
       });
     });