fix(ci): grant secret-scanner reusable its requested job permissions

The reusable's gitleaks job requests pull-requests: write + actions:
read; a called workflow cannot exceed the caller's grant, so wrappers
granting only contents: read die at startup_failure on every run.
Estate sweep; root cause fixed in standards#472.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/secret-scanner.yml

@@ -15,5 +15,13 @@ permissions:
 
 jobs:
   scan:
+    # The reusable's gitleaks job requests pull-requests: write (PR
+    # summary comments) and actions: read. A called workflow cannot
+    # exceed the caller's grant - without these, every run dies at
+    # startup_failure. See standards#472.
+    permissions:
+      contents: read
+      pull-requests: write
+      actions: read
     uses: hyperpolymath/standards/.github/workflows/secret-scanner-reusable.yml@d135b05bfc647d0c0fbfedc7e80f37ea50f49236
-    secrets: inherit
+    secrets: inherit