fix(ci): update secret-scanner SHA to @7fdc2705df74b4e352d2a1cde3e87a5923fdf329

Update secret-scanner-reusable.yml SHA to @7fdc2705df74b4e352d2a1cde3e87a5923fdf329 + remove squisher-corpus placeholders

Part of estate-wide standards#426 remediation.

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

Author: hyperpolymath

.github/workflows/secret-scanner.yml

@@ -19,5 +19,5 @@ jobs:
     # caller must grant at least that or the run startup-fails.
     permissions:
       contents: read
-    uses: hyperpolymath/standards/.github/workflows/secret-scanner-reusable.yml@fcb8669169b4e9f5d9848608df880ae5fae812b4 # main 2026-08-04 (lockfile-bearing ref: actions.lock required by caller-side enforcement, standards#570)
+    uses: hyperpolymath/standards/.github/workflows/secret-scanner-reusable.yml@7fdc2705df74b4e352d2a1cde3e87a5923fdf329 # main 2026-08-04 (lockfile-bearing ref: actions.lock required by caller-side enforcement, standards#570)
     secrets: inherit