## What changed
- Add `RemoteEnvironmentOptions` and `upsert_environment_with_options` so embedding hosts can attach trusted HTTP headers to remote exec-server WebSocket handshakes.
- Preserve the headers across session reconnects while redacting them from debug output.
- Reject invalid, duplicate, and WebSocket-controlled headers, and require `wss://` for non-loopback destinations.
- Connect header-bearing loopback WebSockets directly, with DNS results restricted to loopback addresses.
## Testing
- Cover header validation and redaction, delivery on initial connections and reconnects, and loopback destination enforcement.
GitOrigin-RevId: f2e2b0456c8e33c13fd8ab4ee040a8b5c15e885d