feat: implement notification system with Mailgun email integration

- Add notifications table with migration
- Create NotificationService with area-of-interest matching
- Integrate Mailgun for email delivery
- Add notification API endpoints (get, mark as read, unread count)
- Create scheduled jobs for event reminders and cleanup
- Build NotificationBell component for frontend
- Add notification triggers for reports and events
- Implement comprehensive test script
- Update Header with notification bell
- Add email templates with HTML formatting

Requirements satisfied:
- 10.1: Users can define areas of interest (1-50km radius)
- 10.2: Notifications sent within 10 minutes
- 10.3: Notifications for new reports/events in user area
- 10.4: Configurable notification preferences (email/in-app)

Task 33 completed

server/prisma/schema.prisma

@@ -27,6 +27,7 @@ model User {
   reports            Report[]
   cleanedReports     Report[]            @relation("CleanedByUser")
   verifications      Verification[]
+  notifications      Notification[]
 
   @@index([clerkId], map: "idx_clerk_id")
   @@index([email], map: "idx_email")
@@ -198,3 +199,39 @@ enum reports_verification_status {
   verified
   disputed
 }
+
+model Notification {
+  id          String                      @id @default(dbgenerated("(uuid())")) @db.VarChar(36)
+  userId      String                      @map("user_id") @db.VarChar(36)
+  type        notifications_type
+  title       String                      @db.VarChar(255)
+  message     String                      @db.Text
+  relatedId   String?                     @map("related_id") @db.VarChar(36)
+  relatedType notifications_related_type? @map("related_type")
+  latitude    Decimal?                    @db.Decimal(10, 8)
+  longitude   Decimal?                    @db.Decimal(11, 8)
+  read        Boolean                     @default(false)
+  emailSent   Boolean                     @default(false) @map("email_sent")
+  createdAt   DateTime?                   @default(now()) @map("created_at") @db.Timestamp(0)
+  user        User                        @relation(fields: [userId], references: [id], onDelete: Cascade, onUpdate: NoAction, map: "notifications_ibfk_1")
+
+  @@index([userId], map: "idx_user_id")
+  @@index([createdAt], map: "idx_created_at")
+  @@index([read], map: "idx_read")
+  @@index([type], map: "idx_type")
+  @@index([latitude, longitude], map: "idx_lat_lng")
+  @@map("notifications")
+}
+
+enum notifications_type {
+  new_report
+  new_event
+  event_reminder
+  report_verified
+  report_disputed
+}
+
+enum notifications_related_type {
+  report
+  event
+}