fix: restore terminal state on exit to prevent mouse escape sequence …

[wangliang01]

…garbage

After the TUI exits, the terminal was left with mouse tracking enabled (\x1b[?1003l / \x1b[?1006l SGR mode), causing subsequent terminal input to print raw escape sequences like ^[<35;61;11M instead of being interpreted normally.

Root cause: renderer.destroy() relies on native destroyRenderer() to send the mouse-disable sequences, but process.exit() in index.ts fires before those writes are flushed to stdout.

Fixes:

• exit.tsx: explicitly write mouse-disable + cursor-restore sequences to stdout before renderer.destroy(), and register a process 'exit' handler as a last-resort guarantee that fires synchronously on process exit.
• prompt/index.tsx + session/index.tsx: add double-confirm for Ctrl+C exit (press twice within 3 s) matching the behaviour of claude code and similar TUI tools; inline hint replaces the toast for the first press.
• win32.ts: tighten the ENABLE_PROCESSED_INPUT enforcement poll from 100 ms to 16 ms so the guard reacts faster after console-mode resets.

Issue for this PR

Closes #13276

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

When the user exits opencode (Ctrl+C twice), the terminal was left in a broken state: mouse tracking escape sequences continued to be emitted as visible garbage text (^[<35;61;11M) because the native renderer cleanup didn't finish before process.exit() terminated the process.

This PR fixes the issue in two layers:

1. Explicit terminal reset before renderer.destroy() (exit.tsx): writes the mouse-disable sequences (?1003l, ?1006l, ?1000l) and cursor-restore (?25h) directly to stdout synchronously, so they are guaranteed to flush regardless of whether the native cleanup runs in time.

2. process.on('exit', ...) last-resort handler (exit.tsx): the exit event fires synchronously right before the Node/Bun process terminates, giving a second chance to write the reset sequences even if process.exit() is called from an unexpected path.

3. Double-confirm Ctrl+C exit (prompt/index.tsx, session/index.tsx): instead of exiting immediately on the first Ctrl+C, the user now has to press it twice within 3 seconds — the same UX as Claude Code and similar tools. The first press shows an inline hint in the status bar rather than a floating toast.

4. Faster Windows console-mode enforcement (win32.ts): the ENABLE_PROCESSED_INPUT guard poll interval is reduced from 100 ms to 16 ms so it catches and reverts console-mode resets more promptly on Windows Terminal.

How did you verify your code works?

Tested manually on Windows 11 + Windows Terminal v1.21:

1. Started opencode, ran a prompt, then pressed Ctrl+C twice to exit. After exiting, typed freely in the terminal — previously this produced lines of ^[<35;61;11M ... garbage; after the fix the terminal is clean.

2. Pressed Ctrl+C once with an empty prompt — confirmed the inline hint ctrl+c again to exit appeared in the status bar and auto-dismissed after ~3 s.

3. Pressed Ctrl+C twice quickly — confirmed the app exited cleanly with no garbage output.

4. During an active session, verified Escape still interrupts the running session and Ctrl+C still triggers the two-step exit flow (not session interrupt).

5. Ran bun typecheck in packages/opencode — no type errors.

Screenshots / recordings

If this is a UI change, please include a screenshot or recording.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

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