Revert "Update MCP Web Search server URL in prod config"

This reverts commit 0eb8216.

Author: gary149

chart/env/prod.yaml

@@ -81,7 +81,7 @@ envVars:
   LLM_ROUTER_ENABLE_TOOLS: "true"
   LLM_ROUTER_TOOLS_MODEL: "moonshotai/Kimi-K2-Instruct-0905"
   MCP_SERVERS: >
-    [{"name": "Web Search", "url": "https://victor-websearch.hf.space/gradio_api/mcp/sse"}, {"name": "Hugging Face", "url": "https://hf.co/mcp?login"}]
+    [{"name": "Web Search (Exa)", "url": "https://mcp.exa.ai/mcp"}, {"name": "Hugging Face", "url": "https://hf.co/mcp?login"}]
   PUBLIC_LLM_ROUTER_DISPLAY_NAME: "Omni"
   PUBLIC_LLM_ROUTER_LOGO_URL: "https://cdn-uploads.huggingface.co/production/uploads/5f17f0a0925b9863e28ad517/C5V0v1xZXv6M7FXsdJH9b.png"
   PUBLIC_LLM_ROUTER_ALIAS_ID: "omni"