Email queue + async sending; legal settings and placeholders

- Add in-memory email queue with rate limiting (MAX_EMAILS_PER_HOUR)
- Bulk send to event attendees now queues and returns immediately
- Frontend shows 'Emails are being sent in the background'
- Legal pages, settings, and placeholders updates

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/routes/emails.ts

@@ -5,6 +5,7 @@ import { requireAuth } from '../lib/auth.js';
 import { getNow, generateId } from '../lib/utils.js';
 import emailService from '../lib/email.js';
 import { getTemplateVariables, defaultTemplates } from '../lib/emailTemplates.js';
+import { getQueueStatus } from '../lib/emailQueue.js';
 
 const emailsRouter = new Hono();
 
@@ -195,7 +196,7 @@ emailsRouter.get('/templates/:slug/variables', requireAuth(['admin', 'organizer'
 
 // ==================== Email Sending Routes ====================
 
-// Send email using template to event attendees
+// Send email using template to event attendees (non-blocking, queued)
 emailsRouter.post('/send/event/:eventId', requireAuth(['admin', 'organizer']), async (c) => {
   const { eventId } = c.req.param();
   const user = (c as any).get('user');
@@ -206,7 +207,8 @@ emailsRouter.post('/send/event/:eventId', requireAuth(['admin', 'organizer']), a
     return c.json({ error: 'Template slug is required' }, 400);
   }
   
-  const result = await emailService.sendToEventAttendees({
+  // Queue emails for background processing instead of sending synchronously
+  const result = await emailService.queueEventEmails({
     eventId,
     templateSlug,
     customVariables,
@@ -411,4 +413,10 @@ emailsRouter.post('/test', requireAuth(['admin']), async (c) => {
   return c.json(result);
 });
 
+// Get email queue status
+emailsRouter.get('/queue/status', requireAuth(['admin']), async (c) => {
+  const status = getQueueStatus();
+  return c.json({ status });
+});
+
 export default emailsRouter;