The installer symlinked a RELATIVE target (../../scripts/pre-push), which only
resolves for a standard <repo>/.git/hooks layout — it breaks in git worktrees
or when .git is a file/elsewhere (both used by the agent harness), and assumed
.git/hooks already exists.
Resolve the real hooks dir via 'git rev-parse --git-path hooks' (worktree-safe),
mkdir -p it, and symlink to the ABSOLUTE source path so it works regardless of
where the hooks dir lives. Also verify pre-push exists + is executable.
Tested: installs, link resolves to scripts/pre-push, idempotent.
