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/encryption.ts

@@ -97,7 +97,11 @@ export class CredentialEncryption {
    */
   async encrypt(data: Record<string, string>): Promise<string> {
     if (!this.key) {
-      throw new Error('Encryption not initialized. Call init() first.');
+      await this.init();
+    }
+    const key = this.key;
+    if (!key) {
+      throw new Error('Encryption key initialization failed.');
     }
 
     const iv = crypto.getRandomValues(new Uint8Array(this.ivLength));
@@ -105,7 +109,7 @@ export class CredentialEncryption {
 
     const ciphertext = await crypto.subtle.encrypt(
       { name: this.algorithm, iv },
-      this.key,
+      key,
       encoded
     );
 
@@ -120,9 +124,15 @@ export class CredentialEncryption {
   /**
    * Decrypt a base64 string back to credentials object
    */
-  async decrypt(encrypted: string): Promise<Record<string, string>> {
+  async decrypt<T extends Record<string, string> = Record<string, string>>(
+    encrypted: string,
+  ): Promise<T> {
     if (!this.key) {
-      throw new Error('Encryption not initialized. Call init() first.');
+      await this.init();
+    }
+    const key = this.key;
+    if (!key) {
+      throw new Error('Encryption key initialization failed.');
     }
 
     const combined = this.base64ToBytes(encrypted);
@@ -133,12 +143,12 @@ export class CredentialEncryption {
 
     const decrypted = await crypto.subtle.decrypt(
       { name: this.algorithm, iv },
-      this.key,
+      key,
       ciphertext
     );
 
     const decoded = new TextDecoder().decode(decrypted);
-    return JSON.parse(decoded);
+    return JSON.parse(decoded) as T;
   }
 
   /**