tui: remove the win32 ENABLE_PROCESSED_INPUT ffi shim

[Jarred-Sumner]

Issue for this PR

Refactor — removes a workaround for oven-sh/bun#31941 / #13052-era Bun behaviour. No opencode issue.

Type of change

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

What does this PR do?

Heads up: this is speculative and Claude wrote it; it has not been run on Windows. Posting it from the Bun side because we think the shim is redundant and want to know if it isn't.

Deletes packages/tui/src/terminal-win32.{ts,bun.ts,node.ts} and its two call sites (win32DisableProcessedInput() after createCliRenderer(), win32FlushInputBuffer() at exit). The polling win32InstallCtrlCGuard() already had no callers on v2.

Why it shouldn't be needed: opentui's renderer calls process.stdin.setRawMode(true). On Windows, in both Bun and Node, that's libuv uv_tty_set_mode(UV_TTY_MODE_RAW_VT) → SetConsoleMode(stdin, ENABLE_WINDOW_INPUT | ENABLE_VIRTUAL_TERMINAL_INPUT), which already clears ENABLE_PROCESSED_INPUT, so Ctrl+C arrives as \x03 on stdin and no CTRL_C_EVENT is generated. Neither runtime re-adds the flag afterwards. The shim re-did that by hand via dlopen("kernel32.dll"), and its old 100 ms Get/SetConsoleMode poller is what triggered oven-sh/bun#31941.

Bun fixes that landed after #13052: oven-sh/bun#30288 (process.stdin.isRaw never set on Windows → teardown paths re-cooked stdin on a later tick), oven-sh/bun#33527 (raw-mode state per handle). The remaining related Bun bug — bun run <script> / the global-bin .exe shim exiting on CTRL_C_EVENT while the child keeps running (oven-sh/bun#11400) — is oven-sh/bun#39729; it only affects a raw-mode TUI if something else turned ENABLE_PROCESSED_INPUT back on.

If Ctrl+C regresses on Windows with this, we'd rather get a Bun bug report than keep an ffi workaround here.

How did you verify your code works?

Read-through only (Bun's Source__setRawModeStdin → libuv uv_tty_set_mode flags, opentui renderer.ts raw-mode calls). Not run on Windows — needs someone with a Windows box to confirm Ctrl+C still clears the prompt / exits.

Screenshots / recordings

n/a

Checklist

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

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[github-actions]

Hey! Your PR title tui: use bun:ffi "buffer" arg type instead of ptr() doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.