fix(loyalty): resolve critical production readiness issues

- Add pessimistic locking (SELECT FOR UPDATE) on card write operations
  to prevent race conditions in stamp_service and points_service
- Replace 16 console.log/error/warn calls with LogConfig.createLogger()
  in 3 storefront JS files (dashboard, history, enroll)
- Delete all stale lu.json locale files across 8 modules (lb is the
  correct ISO 639-1 code for Luxembourgish)
- Update architecture rules and docs to reference lb.json not lu.json
- Add production-readiness.md report for loyalty module

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.architecture-rules/module.yaml

@@ -141,7 +141,7 @@ module_rules:
           en.json
           de.json
           fr.json
-          lu.json
+          lb.json
 
       Translation keys are namespaced as {module}.key_name
     pattern:
@@ -269,14 +269,14 @@ module_rules:
       Module locales/ directory should have translation files for
       all supported languages to ensure consistent i18n.
 
-      Supported languages: en, de, fr, lu
+      Supported languages: en, de, fr, lb
 
       Structure:
         app/modules/<code>/locales/
         ├── en.json
         ├── de.json
         ├── fr.json
-        └── lu.json
+        └── lb.json
 
       Missing translations will fall back to English, but it's
       better to have all languages covered.
@@ -286,7 +286,7 @@ module_rules:
         - "en.json"
         - "de.json"
         - "fr.json"
-        - "lu.json"
+        - "lb.json"
 
   - id: "MOD-007"
     name: "Module definition must match directory structure"