refactor: use MCPToolset instead of deprecated mcp_servers param

- Switch from Agent(mcp_servers=[...]) to Agent(tools=[MCPToolset(...)])
- Add WEB_MCP_ENABLED + FIRECRAWL_BASE to supervisord agent env
- Fixes deprecation warning in livekit-agents 1.7

supervisord.conf

@@ -27,7 +27,9 @@ environment=
     AZURE_TTS_VOICE="%(ENV_AZURE_TTS_VOICE)s",
     GEMMA_BASE_URL="%(ENV_GEMMA_BASE_URL)s",
     GEMMA_MODEL="%(ENV_GEMMA_MODEL)s",
-    GEMMA_API_KEY="%(ENV_GEMMA_API_KEY)s"
+    GEMMA_API_KEY="%(ENV_GEMMA_API_KEY)s",
+    WEB_MCP_ENABLED="%(ENV_WEB_MCP_ENABLED)s",
+    FIRECRAWL_BASE="%(ENV_FIRECRAWL_BASE)s"
 
 [program:web]
 command=/usr/sbin/nginx -g "daemon off;"