Add extensive form tests and enhanced error handling for auth components.

- Introduced comprehensive tests for `RegisterForm`, `PasswordResetRequestForm`, and `PasswordResetConfirmForm` covering successful submissions, validation errors, and API error handling.
- Refactored forms to handle unexpected errors gracefully and improve test coverage for edge cases.
- Updated `crypto` and `storage` modules with robust error handling for storage issues and encryption key management.
- Removed unused `axios-mock-adapter` dependency for cleaner dependency management.

frontend/tests/lib/auth/crypto.test.ts

@@ -105,5 +105,53 @@ describe('Crypto Utilities', () => {
       expect(decrypted1).toBe(plaintext);
       expect(decrypted2).toBe(plaintext);
     });
+
+    it('should handle corrupted stored key gracefully', async () => {
+      // Store invalid key data in sessionStorage
+      sessionStorage.setItem('auth_encryption_key', 'invalid-json-data{]');
+
+      // Should generate new key and encrypt successfully
+      const plaintext = 'test data';
+      const encrypted = await encryptData(plaintext);
+      const decrypted = await decryptData(encrypted);
+
+      expect(decrypted).toBe(plaintext);
+      // Key should have been regenerated
+      expect(sessionStorage.getItem('auth_encryption_key')).not.toBe('invalid-json-data{]');
+    });
+
+    it('should handle sessionStorage.setItem errors when storing key', async () => {
+      // Mock setItem to throw error
+      const originalSetItem = sessionStorage.setItem;
+      sessionStorage.setItem = jest.fn(() => {
+        throw new Error('Storage quota exceeded');
+      });
+
+      // Should still work even if key can't be stored
+      const plaintext = 'test data';
+      const encrypted = await encryptData(plaintext);
+
+      // Restore for decryption (which needs to get the key)
+      sessionStorage.setItem = originalSetItem;
+
+      // Should succeed despite storage error (key is kept in memory for the session)
+      expect(encrypted).toBeTruthy();
+    });
+  });
+
+  describe('Error handling', () => {
+    it('should handle clearEncryptionKey errors gracefully', () => {
+      // Mock removeItem to throw error
+      const originalRemoveItem = sessionStorage.removeItem;
+      sessionStorage.removeItem = jest.fn(() => {
+        throw new Error('Storage access denied');
+      });
+
+      // Should not throw, just warn
+      expect(() => clearEncryptionKey()).not.toThrow();
+
+      // Restore
+      sessionStorage.removeItem = originalRemoveItem;
+    });
   });
 });