Add tests for authentication and security features

- Implement unit tests for password handling in `auth_test.ts`, covering bcrypt and legacy password hashes.
- Create a fake database for user management to facilitate testing of the `AdminHandler`.
- Validate JWT-based identity verification against database records.
- Introduce tests for credential encryption and registry management in `security_test.ts`.
- Ensure registry passwords are securely stored and can be decrypted correctly, including legacy support.
- Add utility functions for password hashing and verification in `auth.ts`.

ts/classes/platform-services/providers/mariadb.ts

@@ -74,7 +74,9 @@ export class MariaDBProvider extends BasePlatformServiceProvider {
     if (dataExists && platformService?.adminCredentialsEncrypted) {
       // Reuse existing credentials from database
       logger.info('Reusing existing MariaDB credentials (data directory already initialized)');
-      adminCredentials = await credentialEncryption.decrypt(platformService.adminCredentialsEncrypted);
+      adminCredentials = await credentialEncryption.decrypt<{ username: string; password: string }>(
+        platformService.adminCredentialsEncrypted,
+      );
     } else {
       // Generate new credentials for fresh deployment
       logger.info('Generating new MariaDB admin credentials');