docs: remove common-cache references from documentation and tooling

Remove all remaining references to common-cache from project documentation,
test workflows, and build tooling after action deletion.

Updated:
- CLAUDE.md: Remove from action catalog (28 → 27 actions)
- README.md: Regenerate catalog without common-cache
- SECURITY.md: Update caching optimization notes
- Test workflows: Remove common-cache test references
- spec_helper.sh: Remove common-cache test helpers
- generate_listing.cjs: Remove from category/language mappings
- update-validators.py: Remove custom validator entry

_tests/integration/workflows/node-setup-test.yml

@@ -5,7 +5,6 @@ on:
   push:
     paths:
       - 'node-setup/**'
-      - 'common-cache/**'
       - '_tests/integration/workflows/node-setup-test.yml'
 
 jobs:
@@ -465,7 +464,7 @@ jobs:
           # 6. Cache dependencies
           if [[ "$CACHE" == "true" ]]; then
             echo "Step 6: Cache dependencies"
-            echo "✓ Would use common-cache action"
+            echo "✓ Would use actions/cache action"
           fi
 
           # 7. Install dependencies