pi's provider hosts include Cloudflare endpoints that relay arbitrary HTTPS #67

Security review of #62: api.cloudflare.com offers the Browser Rendering REST API, which fetches any URL for an account token, and creates AI Gateway custom providers with any base URL that gateway.ai.cloudflare.com then forwards to. With both in pi's manifest, a pane set to Network: Only these providers can relay a GET and a POST to any HTTPS host, which is the widening the setting exists to prevent.

Change: remove both hosts from the default list; docs/isolation.md names them, with Bedrock, Vertex and Azure, as hosts to add yourself. Also document that ~/.pi/agent/*.lock (#63) is writable from every This folder only pane, so one session can hold another pi session's lock: availability only, cleared by deleting the lock.