Add token revocation mechanism and support for logout APIs

This commit introduces a system to revoke tokens by storing their `jti` in a new `RevokedToken` model. It includes APIs for logging out (revoking a current token) and logging out from all devices (revoking all tokens). Additionally, token validation now checks revocation status during the decode process.

backend/app/models/__init__.py

@@ -29,7 +29,7 @@ from .gift import (
 from .email_template import EmailTemplate, TemplateType
 from .notification_log import NotificationLog, NotificationType, NotificationStatus
 from .activity_log import ActivityLog, ActivityType
-
+from .token import RevokedToken
 # Make sure all models are imported above this line
 __all__ = [
     'Base', 'TimestampMixin', 'UUIDMixin',
@@ -40,4 +40,5 @@ __all__ = [
     'EmailTemplate', 'TemplateType',
     'NotificationLog', 'NotificationType', 'NotificationStatus',
     'ActivityLog', 'ActivityType',
+    'RevokedToken',
 ]