feat: Add email verification on signup

apps/api/src/services/NtfyService.ts

@@ -318,6 +318,19 @@ export class NtfyService {
     });
   }
 
+  /**
+   * Notify about failed signup attempt with invalid email - LOW priority
+   */
+  public static async notifyFailedSignupAttempt(email: string, reasons: string[]): Promise<void> {
+    const reasonText = reasons.join(', ');
+    await this.send({
+      title: 'Failed Signup - Invalid Email',
+      message: `Signup attempt blocked for email: ${email}\nReasons: ${reasonText}`,
+      priority: NtfyPriority.LOW,
+      tags: [NtfyTag.WARNING, NtfyTag.SHIELD],
+    });
+  }
+
   /**
    * Notify about new user account created via OAuth - LOW priority
    */