Before registering each .sh hook (validate-commit, session-state, phase-boundary),
check that the target file was actually copied. If the .sh file is missing (e.g.
omitted from the npm package as in v1.32.0), skip registration and emit a warning
instead of writing a broken hook entry that errors on every tool invocation.
Closes#1817
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
