* fix(mobile): bound terminal viewport resubscribe loop with backoff (STA-3337)
An empty scrollback frame with absent host dims was coerced to 80x24, which
never equals a phone viewport, arming a zero-delay unsubscribe/resubscribe
loop (~25/s) that broke long-press gestures and drained battery.
- Absent host dims now hold the stream instead of resubscribing.
- Fit resubscribes are budgeted per handle (3 attempts, escalating backoff)
with an absence-gated refill mirroring the chat-side rearm bound; on
exhaustion the view degrades visibly via toast instead of hot-looping.
- A fresh post-measure match counts as convergence instead of resubscribing.
- setTerminalModes keeps the Map identity when the mode is unchanged, so
same-mode frames no longer re-render the session route.
- Host emits the subscriber viewport as scrollback dims when the snapshot
and PTY size are both unavailable, so current hosts converge immediately.
* fix(mobile): cancel stale viewport retries after convergence
0586bab4f9