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>

frontend/src/services/admin.service.ts

@@ -23,6 +23,9 @@ export interface SystemHealth {
   details: {
     emailQueue: {
       pending: number;
+      processable: number;
+      stuck: number;
+      sent: number;
       failed: number;
     };
     memory: {

frontend/src/services/settings.service.ts

@@ -54,6 +54,8 @@ export interface SystemStatus {
   };
   emailQueue: {
     pending: number;
+    processable: number;
+    stuck: number;
     sent: number;
     failed: number;
   };