Restore web PTY attachment after transient phone or network loss #212

Goal

Resume a terminal attachment with bounded replay and clear recovery feedback instead of creating a second PTY client.

Scope

• Preserve managed tmux sessions across expected process and network interruptions.
• Never duplicate a session, replay a control action, or silently discard a pending approval.

Acceptance

• Resume a terminal attachment with bounded replay and clear recovery feedback instead of creating a second PTY client.
• Cover restart, disconnect, timeout, and duplicate-message paths.
• Export explicit recovery state to the fleet API.

Verification

• go test -race ./internal/web ./internal/pty && npm --prefix frontend test

Dependencies

#210