fix: repair stale Codex hook path

[Pigbibi]

Summary

• repair existing telegram-codex-bot hook entries when their absolute executable path no longer exists
• keep hook installation idempotent without adding duplicate SessionStart hooks
• add regression coverage for stale hook path repair

Tests

• uv run pytest tests/telegram_codex_bot/test_hook.py tests/telegram_codex_bot/test_existing_window_binding.py::test_refresh_session_map_retries_enter_when_first_prompt_is_pending tests/telegram_codex_bot/test_existing_window_binding.py::test_refresh_session_map_retries_enter_when_resume_prompt_is_pending
• uv run ruff check src/ tests/
• uv run pyright src/telegram_codex_bot/
• uv run pytest