fix(hook): use absolute claude hook command

[YOMXXX]

Summary

• register Claude hooks with the current RTK executable absolute path instead of bare rtk hook claude
• recognize absolute native Claude hook commands during idempotency checks and uninstall
• add regression coverage for install, hook-only install, detection, and removal

Fixes #2361

Verification

• cargo +1.93.0 fmt --check
• git diff --check
• cargo +1.93.0 test absolute -- --nocapture
• cargo +1.93.0 test hooks::init -- --nocapture
• cargo +1.93.0 clippy --all-targets
• cargo +1.93.0 test --all -- --skip small_grep_not_worse_than_plain
• CLI smoke with temporary CLAUDE_CONFIG_DIR: rtk init -g --hook-only --auto-patch writes /.../target/debug/rtk hook claude

[YOMXXX]

Follow-up pushed in 15c3f9c to address the Windows CI failures. Root cause was host-platform path parsing: Unix-style absolute hook commands were not considered absolute on Windows. The hook detection now recognizes Unix, Windows drive, and UNC path styles portably, with a Windows-style regression test.\n\nVerification run locally:\n- RED: cargo +1.93.0 test test_hook_already_present_windows_absolute_native_command -- --nocapture failed before the fix\n- cargo +1.93.0 test test_hook_already_present_windows_absolute_native_command -- --nocapture\n- cargo +1.93.0 test test_hook_already_present_absolute_native_command -- --nocapture\n- cargo +1.93.0 test test_remove_hook_from_json_absolute_native_command -- --nocapture\n- cargo +1.93.0 test hooks::init::tests -- --nocapture\n- cargo +1.93.0 fmt --check\n- git diff --check\n- cargo +1.93.0 clippy --all-targets\n- cargo +1.93.0 test --all -- --skip small_grep_not_worse_than_plain