ci: gate pushes on a gitleaks scan of the outgoing commits

No repo here scanned for committed credentials. The hook is self-contained
rather than delegating to a Makefile, because this repo has none and a hook
reaching into a sibling repo breaks the moment this one is cloned elsewhere.

Scans the outgoing range rather than full history: history carries settled
findings — test fixtures, vendored third-party code — and a gate that fails
on something unfixable gets bypassed within a week.

Setting core.hooksPath means pql init must replant its replication shims into
.githooks, which is why they are gitignored here alongside the tracked
pre-push. Same layout pql itself uses.

Co-Authored-By: Claude <noreply@anthropic.com>

.githooks/pre-push

@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+# Secret scan over the commits about to be pushed. Opt in per clone with:
+#
+#   git config core.hooksPath .githooks
+#
+# Self-contained on purpose: this repo has no Makefile, and a hook that
+# depends on one in a sibling repo breaks the moment the repo is cloned
+# anywhere else.
+set -euo pipefail
+
+cd "$(git rev-parse --show-toplevel)"
+
+# A non-login shell — which is what git gives a hook — skips /etc/profile.d
+# and never sees ~/.local/bin, where the gitleaks release tarball lands.
+# Without this the scan reports "not installed" on every push.
+[ -d "$HOME/.local/bin" ] && PATH="$HOME/.local/bin:$PATH"
+
+if ! command -v gitleaks >/dev/null 2>&1; then
+  echo "FAIL secrets — gitleaks not installed, so this check would be a no-op pretending to pass." >&2
+  echo "     https://github.com/gitleaks/gitleaks/releases → ~/.local/bin/gitleaks" >&2
+  exit 1
+fi
+
+# Scan the outgoing range, not full history. History here carries findings
+# that are settled — test fixtures and vendored third-party code — and a gate
+# that fails on something unfixable gets bypassed within a week. What matters
+# is what is about to leave this machine.
+if upstream=$(git rev-parse --abbrev-ref --symbolic-full-name '@{u}' 2>/dev/null); then
+  range="$upstream..HEAD"
+elif git rev-parse --verify --quiet origin/main >/dev/null; then
+  range="origin/main..HEAD"
+else
+  range=""
+fi
+
+if [ -z "$range" ]; then
+  gitleaks dir . --redact --no-banner --exit-code 1 || {
+    echo "FAIL secrets — gitleaks found a credential in the working tree." >&2; exit 1; }
+  exit 0
+fi
+
+[ -n "$(git log --oneline "$range" 2>/dev/null)" ] || exit 0
+
+gitleaks git . --log-opts="$range" --redact --no-banner --exit-code 1 >/dev/null 2>&1 || {
+  echo "FAIL secrets — gitleaks found a credential in the commits being pushed." >&2
+  echo "     inspect (values redacted):  gitleaks git . --log-opts=\"$range\" --redact" >&2
+  echo "     then remove and rotate it, or suppress deliberately:" >&2
+  echo "       inline  '# gitleaks:allow  <reason>'" >&2
+  echo "       or add the fingerprint to .gitleaksignore WITH a reason" >&2
+  exit 1
+}
+echo "  ok   secrets"