ci(secret-scan): canonical estate scanner caller, key scan (D243)

.github/workflows/secret-scanner.yml

@@ -0,0 +1,27 @@
+# SPDX-License-Identifier: MPL-2.0
+# Prevention workflow - scans for hardcoded secrets before they reach main.
+#
+# Calls the estate's shared secret scanner (gitleaks + rust-secrets +
+# shell-secrets). The job key MUST stay `scan`: the estate-wide
+# Secret-Scan-Floor ruleset requires the check context `scan / gitleaks`.
+#
+# No `secrets:` line, deliberately: the reusable references no secrets
+# (gitleaks runs as a checksum-verified binary, not gitleaks-action), so
+# `secrets: inherit` would only hand it every repo and org secret (CWE-250).
+name: Secret Scanner
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  scan:
+    uses: hyperpolymath/standards/.github/workflows/secret-scanner-reusable.yml@74d2f66f575246cf6e313ae7775f44df6e097ff2