* draft
* Adjust IME candidate scrolling and space behavior
* Remove IME buffer label and update remaining counter
* Align Meshtastic handling and stabilize chat UI
- Align Meshtastic send/receive flow: add routing ACK decoding/log mapping, ack timeouts, channel tracking, and richer RX/TX diagnostics.
- Persist and manage PKI peer keys; add PKI backoff on NO_CHANNEL/UNKNOWN_PUBKEY and fall back to PSK when needed.
- Improve chat UI state handling: safer app switching with exit callbacks, active app clearing on menu return, and safer chat container cleanup.
- Fix Contacts → Compose parent selection to avoid UI tree mismatch; add broadcast compose support and refine action button behavior.
- Add UI debug logging for screen/parent validity and child counts to diagnose black-screen/stacking issues.
- Apply timezone offset helpers for display-time formatting and reuse in screenshot timestamps.
* Add changelog entry and time helpers
liu weikai