TUI flickers and disconnects on repeated resize over Termux mobile SSH

Summary

When running opencode TUI over a mobile SSH client (Termux on Android), the UI flickers severely on each app switch, and after several cycles the connection drops entirely.

This is a mobile-SSH-specific variation of #42225 (shrink-layout not re-layouted) combined with #44055 (resize listener leak). The existing issues were reported from desktop/browser contexts; this one documents the same root cause triggered by a mobile SSH client's keyboard-height change.

Reproduction

1. Run opencode on a remote Linux server via SSH from Termux (Android)
2. Type a query to start a streaming response
3. Press the Home button (or swipe to switch away) — the app hides, keyboard collapses, terminal grows
4. Switch back to Termux — the keyboard reappears, terminal shrinks
5. Observe:
   • Flicker: text disappears/reappears during the resize; sidebar/status bar garbled
   • Scrollback corruption: prompt jumps to top of visible area
6. Repeat steps 3–5 5–10 times
7. After ~5–10 cycles, the TUI connection drops (terminal becomes unresponsive, reconnecting doesn't help)

Expected Behavior

• Smooth resize without flicker or scroll jump
• Long-running sessions survive repeated resize events without crashing or disconnecting

Actual Behavior

• Visual corruption on every shrink/grow cycle (stale width, garbled sidebar)
• After multiple cycles, the TUI becomes unresponsive and the SSH session drops

Environment

Analysis

Two compounding issues:

1. #42225 — On terminal shrink, the TUI keeps its stale width. The sidebar/status bar draw at wrong absolute columns, causing garbled text and visual flicker on every resize. Already being fixed upstream (PR #42330 / opentui#1363).

2. #44055 — Resize listener leak. Each app switch adds new SIGWINCH listeners without cleaning up old ones. Over many cycles this causes accumulated memory/EventEmitter warnings and eventually connection instability.

The mobile SSH scenario is especially painful because every keyboard toggle triggers a resize, making the leak and stale layout visible in seconds rather than minutes.

Additional Context

• The Ctrl+L workaround from #42225 was attempted but does not prevent the connection drop over many cycles
• opencode web (headless) works fine over the same SSH session — only the TUI is affected
• The flicker is most visible during streaming (assistant typing); static output briefly flashes before settling