https://app.sendmux.ai/ https://app.sendmux.ai/auth.md https://app.sendmux.ai/.well-known/api-catalog https://app.sendmux.ai/.well-known/oauth-protected-resource/api/v1 https://app.sendmux.ai/.well-known/oauth-authorization-server/agent-auth https://app.sendmux.ai/.well-known/mcp/server-card.json https://app.sendmux.ai/.well-known/agent-skills/index.json https://app.sendmux.ai/api/v1/openapi.json