feat: auto-register walk-in attendees during check-in

- Automatically register users who scan QR code but aren't pre-registered
- Mark walk-in registrations with wasWalkIn flag
- Show different success messages for walk-ins vs pre-registered attendees
- Check in walk-ins immediately upon registration
- Remove 'not registered' error - now handles walk-ins gracefully
- Update both QR scan and manual check-in to support walk-ins

server/src/controllers/eventController.ts

@@ -582,20 +582,12 @@ export const eventController = {
       // Find or create the attendee user
       const attendeeUserId = await findOrCreateUser(clerkUserId);
 
-      // Check in the attendee
+      // Check in the attendee (will auto-register if not registered)
       const result = await eventService.checkInAttendee(id, attendeeUserId);
 
       res.json(result);
     } catch (error: any) {
       console.error('Error checking in attendee:', error);
-      
-      if (error.message.includes('not registered')) {
-        return res.status(404).json({
-          code: 'NOT_REGISTERED',
-          message: error.message,
-          timestamp: new Date().toISOString(),
-        });
-      }
 
       if (error.message.includes('already checked in')) {
         return res.status(409).json({

server/src/services/eventService.ts

@@ -495,7 +495,7 @@ export const eventService = {
 
   async checkInAttendee(eventId: string, userId: string) {
     // Check if user is registered
-    const registration = await prisma.eventRegistration.findUnique({
+    let registration = await prisma.eventRegistration.findUnique({
       where: {
         userId_eventId: {
           userId,
@@ -515,15 +515,49 @@ export const eventService = {
       },
     });
 
+    // If not registered, register them now (walk-in)
     if (!registration) {
-      throw new Error('User is not registered for this event');
+      registration = await prisma.eventRegistration.create({
+        data: {
+          userId,
+          eventId,
+          attended: true, // Check them in immediately
+        },
+        include: {
+          user: {
+            select: {
+              id: true,
+              username: true,
+              firstName: true,
+              lastName: true,
+              avatarUrl: true,
+            },
+          },
+        },
+      });
+
+      return {
+        success: true,
+        username: registration.user.username,
+        firstName: registration.user.firstName,
+        lastName: registration.user.lastName,
+        wasWalkIn: true, // Flag to indicate this was a walk-in registration
+        attendee: {
+          id: registration.id,
+          userId: registration.userId,
+          eventId: registration.eventId,
+          registeredAt: registration.registeredAt || new Date(),
+          attended: registration.attended || false,
+          user: registration.user,
+        },
+      };
     }
 
     if (registration.attended) {
       throw new Error('User is already checked in');
     }
 
-    // Update attendance
+    // Update attendance for pre-registered user
     const updated = await prisma.eventRegistration.update({
       where: {
         userId_eventId: {
@@ -552,6 +586,7 @@ export const eventService = {
       username: updated.user.username,
       firstName: updated.user.firstName,
       lastName: updated.user.lastName,
+      wasWalkIn: false,
       attendee: {
         id: updated.id,
         userId: updated.userId,