fix: resolve email queue discrepancy between admin dashboard and processor

The issue: Admin dashboard showed pending emails that the processor wouldn't
process because they had exceeded retry limits (retry_count >= 3).

Changes:
- Updated backend /admin/system/status to provide detailed email queue stats:
  - pending: total pending emails (as before)
  - processable: emails that will actually be processed (retry_count < 3)
  - stuck: emails that exceeded retry limit but are still pending
- Updated frontend to display stuck emails with warning when present
- Created debug-email-queue.js script to diagnose discrepancies
- Created fix-stuck-emails.js script to handle stuck emails:
  - Can reset retry count, mark as failed, or delete
  - Usage: node fix-stuck-emails.js [reset|fail|delete]

This makes it clear when emails are stuck and won't be processed automatically.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/src/routes/adminSystem.js

@@ -70,8 +70,16 @@ router.get('/status', adminAuth, async (req, res) => {
     
     // Email queue status
     const [pendingEmails] = await db('email_queue').where('status', 'pending').count('* as count');
+    const [processableEmails] = await db('email_queue')
+      .where('status', 'pending')
+      .where('retry_count', '<', 3)
+      .count('* as count');
     const [sentEmails] = await db('email_queue').where('status', 'sent').count('* as count');
     const [failedEmails] = await db('email_queue').where('status', 'failed').count('* as count');
+    const [stuckEmails] = await db('email_queue')
+      .where('status', 'pending')
+      .where('retry_count', '>=', 3)
+      .count('* as count');
 
     // Activity logs count
     const [activityCount] = await db('activity_logs').count('* as count');
@@ -139,6 +147,8 @@ router.get('/status', adminAuth, async (req, res) => {
       },
       emailQueue: {
         pending: pendingEmails.count,
+        processable: processableEmails.count,
+        stuck: stuckEmails.count,
         sent: sentEmails.count,
         failed: failedEmails.count
       },