fix(hooks): prevent terminal I/O blocking from hung Kitty subprocesses

[ozten]

Fix for issue #464.

The StopOrchestrator hook was causing keyboard unresponsiveness for 10-220 seconds after Claude Code sessions ended. This was most severe for users not running Kitty terminal.

Root cause: The tab-state handler executed kitten @ set-tab-color commands that hung indefinitely when no Kitty socket was available. While Promise.race() timeouts were in place, they only abandoned the promise - the subprocess continued running in the background, blocking terminal I/O until it eventually timed out on its own.

Changes:

• Add subprocess.ts utility with explicit process control using Bun.spawn() instead of Bun.$``. This enables killing hung processes with SIGTERM followed by SIGKILL fallback after 2 seconds.

• Refactor tab-state.ts with terminal detection (matching the existing pattern in UpdateTabTitle.hook.ts). Kitty terminals use remote control API with subprocess timeout protection. Other terminals fall back to escape codes for basic title support.

• Apply same terminal detection pattern to SetQuestionTab.hook.ts for consistency across all tab-related hooks.

• Add AbortController timeout protection to voice.ts and SystemIntegrity.ts handlers for defense in depth.

The fix provides three layers of protection:

1. Terminal detection - skip Kitty-specific code entirely for non-Kitty
2. Escape code fallback - basic functionality for all terminals
3. Subprocess control - kill hung processes after 2s timeout (Kitty)

[ozten]

I don't think this PR fixes the garbled screen issue, but it does eliminate the unresponsiveness that reproduced 100% of the time when using PAI without Kitty.

[ozten]

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