MCP proxy Worker: connect via mcp-remote at a dedicated origin

The MCP server is now also served from https://vello-mcp.matteo-3bc.workers.dev — a Cloudflare Worker that proxies every request to the vello-mcp-v2 edge function. This fixes mcp-remote (and any spec-strict MCP client) failing at the token-exchange step with an opaque ServerError: those clients re-run OAuth discovery at the origin root of the server URL, and on *.supabase.co the root /.well-known/* paths belong to Supabase's gateway, so discovery failed and the token request went to the wrong URL. When connecting through the new origin, the OAuth discovery documents and WWW-Authenticate breadcrumb advertise the proxy origin, so every discovery path resolves. Existing claude.ai connectors pointed at the supabase.co URL are unaffected. To connect Claude Desktop via mcp-remote, use the new URL: npx -y mcp-remote https://vello-mcp.matteo-3bc.workers.dev.