Add styled notification emails and round-attached notifications

- Add 15+ styled email templates matching existing invite email design
- Wire up notification triggers in all routers (assignment, round, project, mentor, application, onboarding)
- Add test email button for each notification type in admin settings
- Add round-attached notifications: admins can configure which notification to send when projects enter a round
- Fall back to status-based notifications when round has no configured notification

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/server/services/in-app-notification.ts

@@ -6,7 +6,7 @@
  */
 
 import { prisma } from '@/lib/prisma'
-import { sendNotificationEmail } from '@/lib/email'
+import { sendStyledNotificationEmail } from '@/lib/email'
 
 // Notification priority levels
 export type NotificationPriority = 'low' | 'normal' | 'high' | 'urgent'
@@ -218,7 +218,7 @@ export async function createNotification(
   })
 
   // Check if we should also send an email
-  await maybeSendEmail(userId, type, title, message, linkUrl)
+  await maybeSendEmail(userId, type, title, message, linkUrl, metadata)
 }
 
 /**
@@ -267,7 +267,7 @@ export async function createBulkNotifications(params: {
 
   // Check email settings and send emails
   for (const userId of userIds) {
-    await maybeSendEmail(userId, type, title, message, linkUrl)
+    await maybeSendEmail(userId, type, title, message, linkUrl, metadata)
   }
 }
 
@@ -373,7 +373,8 @@ async function maybeSendEmail(
   type: string,
   title: string,
   message: string,
-  linkUrl?: string
+  linkUrl?: string,
+  metadata?: Record<string, unknown>
 ): Promise<void> {
   try {
     // Check if email is enabled for this notification type
@@ -396,16 +397,21 @@ async function maybeSendEmail(
       return
     }
 
-    // Send the email
-    const subject = emailSetting.emailSubject || title
-    const body = emailSetting.emailTemplate
-      ? emailSetting.emailTemplate
-          .replace('{title}', title)
-          .replace('{message}', message)
-          .replace('{link}', linkUrl || '')
-      : message
-
-    await sendNotificationEmail(user.email, user.name || 'User', subject, body, linkUrl)
+    // Send styled email with full context
+    // The styled template will use metadata for rich content
+    // Subject can be overridden by admin settings
+    await sendStyledNotificationEmail(
+      user.email,
+      user.name || 'User',
+      type,
+      {
+        title,
+        message,
+        linkUrl,
+        metadata,
+      },
+      emailSetting.emailSubject || undefined
+    )
   } catch (error) {
     // Log but don't fail the notification creation
     console.error('[Notification] Failed to send email:', error)