Remove MSW handlers and update demo credentials for improved standardization

- Deleted `admin.ts`, `auth.ts`, and `users.ts` MSW handler files to streamline demo mode setup.
- Updated demo credentials logic in `DemoCredentialsModal` and `DemoModeBanner` for stronger password requirements (≥12 characters).
- Refined documentation in `CLAUDE.md` to align with new credential standards and auto-generated MSW workflows.

frontend/src/app/[locale]/demos/page.tsx

@@ -52,7 +52,7 @@ const demoCategories = [
     features: ['Login & logout', 'Registration', 'Password reset', 'Session tokens'],
     credentials: {
       email: 'demo@example.com',
-      password: 'Demo123!',
+      password: 'DemoPass1234!',
       role: 'Regular User',
     },
   },
@@ -64,7 +64,7 @@ const demoCategories = [
     features: ['Profile editing', 'Password changes', 'Active sessions', 'Preferences'],
     credentials: {
       email: 'demo@example.com',
-      password: 'Demo123!',
+      password: 'DemoPass1234!',
       role: 'Regular User',
     },
   },
@@ -76,7 +76,7 @@ const demoCategories = [
     features: ['User management', 'Analytics charts', 'Bulk operations', 'Organization control'],
     credentials: {
       email: 'admin@example.com',
-      password: 'Admin123!',
+      password: 'AdminPass1234!',
       role: 'Admin',
     },
   },