Implement real campaign suspension notifications with email and in-app delivery

[Just-Bamford]

Problem Statement

AdminService.suspendCampaign had a critical notification failure that left campaign creators completely unaware of suspensions:

this pr Closes #6

• No Real Email Delivery: The sendCampaignSuspensionEmail method only logged to console with a TODO comment - no actual email was sent
• Invalid Email Address: Used a synthetic email creator-${creatorId}@platform.internal that cannot receive mail
• No In-App Notification: Creators had zero in-app visibility of the suspension
• Silent Failures: API returned 200 OK even when notifications weren't sent, hiding the problem from admins
• User Impact: Campaigns could be frozen without creators knowing, blocking support requests, refunds, and legitimate appeals

Result: Admins could confidently suspend a campaign, see the API return success, but the creator receives nothing - leaving them confused and unable to respond.

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Solution Implemented

1. Professional Email Template

Added campaignSuspensionTemplate to email-templates.ts:

• Branded HTML email with warning banner
• Clear display of campaign title and suspension reason
• "What this means" section explaining the impact
• Bullet points: campaign hidden, donations blocked, funds remain secure
• Support contact button with configurable email
• Professional footer with compliance text

2. Real Email Delivery via Bull Queue

Replaced the TODO stub in notifications.service.ts with full implementation:

• Fetches real creator from database using prisma.user.findUnique
• Validates creator exists and has valid email address
• Renders HTML template with suspension details
• Queues email job via Bull (QUEUE_EMAIL) for async processing
• Bypasses user notification preferences (suspension emails are critical)
• Comprehensive logging at each step

3. In-App Notification Creation

Creates a persistent notification in the database:

• Type: CAMPAIGN_UPDATED (using existing enum)
• Title: "Campaign Suspended"
• Message: Includes campaign title and suspension reason
• Links to campaign via relatedId field
• Marked as unread by default
• Visible in creator's notification center

4. Graceful Error Handling

Updated AdminService.suspendCampaign:

• Campaign suspension and audit log happen first (transactional)
• Notification sending wrapped in try-catch block
• Returns notificationSent: boolean flag to indicate delivery status
• Logs errors but doesn't throw (campaign is already suspended)
• Allows admins to see notification failures and take manual action

5. API Transparency

Updated AdminController.suspendCampaign:

• Returns { message: string, notificationSent: boolean }
• Frontend can check notificationSent flag
• If false, frontend should alert admin to manually notify creator
• Maintains clear separation: suspension succeeded, notification may have failed

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Notification Flow

Admin suspends campaign
↓
Update campaign.status = CANCELLED
↓
Write audit log
↓
[TRY]
Fetch creator from database (prisma.user.findUnique)
↓
Validate email exists
↓
Render HTML template with suspension data
↓
Queue email job via Bull (QUEUE_EMAIL)
↓
Create in-app notification (prisma.notification.create)
↓
Log success
↓
Return { message: "...", notificationSent: true }
[CATCH]
Log error (creator not found, no email, queue failure)
↓
Return { message: "...", notificationSent: false }