feat(phases): implement webhooks (6.1), email (7.1), user preferences (7.2)

- Phase 6.1: WebhookConfig model, CRUD router (/api/v1/webhooks, admin-only),
  dispatch_webhook() with HMAC signing; integrated into test validation,
  campaign completion, and MITRE sync job
- Phase 7.1: SMTP email service with send_test_validated_email,
  send_campaign_completed_email, send_new_mitre_techniques_email;
  notify_role_with_email() added to notification_service
- Phase 7.2: notification_preferences and jira_account_id on User model;
  PATCH /users/me/preferences endpoint; Alembic migrations b031phase6 and b032phase7

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/schemas/user.py

@@ -121,6 +121,13 @@ class PasswordChange(BaseModel):
         return _validate_password_strength(v)
 
 
+class UserPreferencesUpdate(BaseModel):
+    """Payload for updating current user's notification preferences and Jira account."""
+
+    notification_preferences: dict | None = None
+    jira_account_id: str | None = None
+
+
 class UserOut(BaseModel):
     """Complete representation returned by the API."""
 
@@ -132,5 +139,7 @@ class UserOut(BaseModel):
     must_change_password: bool = True
     created_at: datetime | None = None
     last_login: datetime | None = None
+    notification_preferences: dict | None = None
+    jira_account_id: str | None = None
 
     model_config = ConfigDict(from_attributes=True)