feat: implement email-optional authentication

- Make email field optional in database schema
- Update user creation to handle null emails
- Enhance notification service to gracefully skip email for users without email addresses
- Add validation in email service for null/empty emails
- Create comprehensive documentation for Clerk configuration
- Add test script for email-optional functionality
- Update all user creation points (userService, eventController, reportController)

Users can now sign up with just username and password. Email notifications
are gracefully skipped for users without email addresses, while in-app
notifications continue to work for all users.

Closes: Email-optional authentication requirement

server/src/scripts/testEmailOptional.ts

@@ -0,0 +1,118 @@
+/**
+ * Test script for email-optional functionality
+ * 
+ * This script tests:
+ * 1. Creating users without email addresses
+ * 2. Notification delivery for users without email
+ * 3. Email service handling of null emails
+ * 
+ * Run with: npx ts-node src/scripts/testEmailOptional.ts
+ */
+
+import prisma from '../config/database';
+import { notificationService } from '../services/notificationService';
+import { emailService } from '../services/emailService';
+
+async function testEmailOptional() {
+  console.log('🧪 Testing Email-Optional Functionality\n');
+
+  try {
+    // Test 1: Create a test user without email
+    console.log('1️⃣ Creating test user without email...');
+    const testUser = await prisma.user.create({
+      data: {
+        clerkId: `test_${Date.now()}`,
+        email: null, // No email
+        username: `testuser_${Date.now()}`,
+        firstName: 'Test',
+        lastName: 'User',
+        notificationEmail: true, // Wants email notifications but has no email
+        notificationInApp: true,
+      },
+    });
+    console.log(`✅ Created user: ${testUser.username} (ID: ${testUser.id})`);
+    console.log(`   Email: ${testUser.email || 'NULL'}`);
+    console.log(`   Notification preferences: email=${testUser.notificationEmail}, inApp=${testUser.notificationInApp}\n`);
+
+    // Test 2: Create a notification for this user
+    console.log('2️⃣ Creating notification for user without email...');
+    const notification = await notificationService.createNotification({
+      userId: testUser.id,
+      type: 'new_report',
+      title: 'Test Notification',
+      message: 'This is a test notification for a user without email.',
+    });
+    console.log(`✅ Created notification: ${notification.id}`);
+    console.log(`   Email sent: ${notification.emailSent}\n`);
+
+    // Test 3: Try to send email notification (should be skipped gracefully)
+    console.log('3️⃣ Attempting to send email notification...');
+    const result = await emailService.sendNotificationEmail(
+      testUser.email || '',
+      testUser.firstName,
+      'Test Email',
+      'This should not be sent because user has no email.'
+    );
+    console.log(`✅ Email send result: ${result}`);
+    console.log(`   Expected: false (no email address)\n`);
+
+    // Test 4: Create a user WITH email for comparison
+    console.log('4️⃣ Creating test user WITH email...');
+    const testUserWithEmail = await prisma.user.create({
+      data: {
+        clerkId: `test_email_${Date.now()}`,
+        email: `test_${Date.now()}@example.com`,
+        username: `testuser_email_${Date.now()}`,
+        firstName: 'Test',
+        lastName: 'WithEmail',
+        notificationEmail: true,
+        notificationInApp: true,
+      },
+    });
+    console.log(`✅ Created user: ${testUserWithEmail.username} (ID: ${testUserWithEmail.id})`);
+    console.log(`   Email: ${testUserWithEmail.email}\n`);
+
+    // Test 5: Query users for email notifications
+    console.log('5️⃣ Querying users eligible for email notifications...');
+    const usersForEmail = await prisma.user.findMany({
+      where: {
+        notificationEmail: true,
+        email: { not: null },
+      },
+      select: {
+        id: true,
+        username: true,
+        email: true,
+      },
+    });
+    console.log(`✅ Found ${usersForEmail.length} users eligible for email notifications`);
+    console.log(`   Users with email: ${usersForEmail.filter(u => u.email).length}`);
+    console.log(`   Users without email: ${usersForEmail.filter(u => !u.email).length}\n`);
+
+    // Cleanup
+    console.log('🧹 Cleaning up test data...');
+    await prisma.notification.deleteMany({
+      where: { userId: { in: [testUser.id, testUserWithEmail.id] } },
+    });
+    await prisma.user.deleteMany({
+      where: { id: { in: [testUser.id, testUserWithEmail.id] } },
+    });
+    console.log('✅ Cleanup complete\n');
+
+    console.log('✅ All tests passed!\n');
+    console.log('Summary:');
+    console.log('- Users can be created without email addresses');
+    console.log('- Notifications are created for users without email');
+    console.log('- Email sending is gracefully skipped for users without email');
+    console.log('- Database queries correctly filter users by email presence');
+
+  } catch (error: any) {
+    console.error('❌ Test failed:', error.message);
+    console.error(error);
+  } finally {
+    await prisma.$disconnect();
+  }
+}
+
+// Run the test
+testEmailOptional();