feat: web access via MCP (Firecrawl search/scrape) + mcp server attach support

- agent/web_mcp.py: stdio MCP server exposing web_search and web_scrape,
  backed by the self-hosted Firecrawl stack on xNAS (no API key needed)
- agent.py: Agent now attaches mcp_servers built from config; EXTRA_MCP_SERVERS
  env var allows adding arbitrary HTTP/SSE MCP servers as JSON
- Dockerfile: installs livekit-agents[mcp], copies web_mcp.py
- .env.example: WEB_MCP_ENABLED, FIRECRAWL_BASE, EXTRA_MCP_SERVERS documented

web/index.html

@@ -37,6 +37,7 @@
         </div>
 
         <div class="status" id="status">Disconnected</div>
+        <div class="status" id="micLevel" style="font-size: 0.8em;"></div>
 
         <div class="transcript" id="transcript">
             <div class="transcript-header">Conversation</div>
@@ -44,7 +45,7 @@
         </div>
     </div>
 
-    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/index.umd.min.js"></script>
+    <script src="livekit-client.umd.js"></script>
     <script src="app.js"></script>
 </body>
 </html>