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/legal-pages.ts

@@ -3,6 +3,7 @@ import { db, dbGet, dbAll, legalPages } from '../db/index.js';
 import { eq, desc } from 'drizzle-orm';
 import { requireAuth } from '../lib/auth.js';
 import { getNow, generateId } from '../lib/utils.js';
+import { replaceLegalPlaceholders } from '../lib/legal-placeholders.js';
 import fs from 'fs';
 import path from 'path';
 
@@ -171,12 +172,15 @@ legalPagesRouter.get('/:slug', async (c) => {
     // Get localized content with fallback
     const { title, contentMarkdown } = getLocalizedContent(page, locale);
     
+    // Replace legal placeholders before returning
+    const processedContent = await replaceLegalPlaceholders(contentMarkdown, page.updatedAt);
+    
     return c.json({
       page: {
         id: page.id,
         slug: page.slug,
         title,
-        contentMarkdown,
+        contentMarkdown: processedContent,
         updatedAt: page.updatedAt,
         source: 'database',
       }
@@ -195,11 +199,14 @@ legalPagesRouter.get('/:slug', async (c) => {
       ? (titles?.es || titles?.en || slug)
       : (titles?.en || titles?.es || slug);
     
+    // Replace legal placeholders in filesystem content too
+    const processedContent = await replaceLegalPlaceholders(content);
+    
     return c.json({
       page: {
         slug,
         title,
-        contentMarkdown: content,
+        contentMarkdown: processedContent,
         source: 'filesystem',
       }
     });