`make hooks` already sets `core.hooksPath=.githooks/`, and the
pre-push gate at `.githooks/pre-push` already runs `make push-check`
— but the pql-installed pre-commit and post-merge shims live at
`.git/hooks/`, which take precedence and silently disable .githooks/.
Add the missing pre-commit / post-merge shims under .githooks/ so
`make hooks` becomes a single-step install: pre-push enforcement,
pql planning-state auto-export on commit, and auto-import on pull
all fire from the canonical .githooks/ location.
Co-Authored-By: Claude <noreply@anthropic.com>