refactor(tui): remove unused win32 ctrl-c guard

[Hona]

Summary

• remove the orphaned Windows Ctrl+C guard and its 100 ms polling interval from the Bun and Node TUI implementations
• stop exporting the unused guard
• pass the remaining GetConsoleMode output array through Bun FFI's buffer argument directly

The guard lost its final call site when the legacy V1 TUI startup path was removed in a43de3f. V2 still performs its active one-shot console mode clear after renderer creation.

Testing

• bun typecheck in packages/tui
• bun test in packages/tui (732 passed, 6 skipped)
• repository pre-push typecheck (33 tasks passed)

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[Hona]

Superseded by #43604, which removes the entire OpenCode Win32 console-mode shim now that OpenTUI 0.5.4 owns raw-mode setup and cross-platform input flushing.