feat: add BullMQ job queue with admin monitoring UI

- Add BullMQ to backend; mail jobs (verification, password reset) now enqueued instead of sent inline
- Mail worker processes jobs with 3-attempt exponential backoff retry
- Admin GraphQL resolvers: adminQueues, adminQueueJobs, adminRetryJob, adminRemoveJob, adminPauseQueue, adminResumeQueue
- Admin frontend page at /admin/queues: queue cards with counts, job table with status filter, retry/remove/pause actions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/lib/i18n/locales/en.ts

@@ -913,6 +913,7 @@ export default {
       articles: "Articles",
       comments: "Comments",
       recordings: "Recordings",
+      queues: "Queues",
     },
     common: {
       save_changes: "Save changes",
@@ -1058,6 +1059,36 @@ export default {
       delete_success: "Recording deleted",
       delete_error: "Failed to delete recording",
     },
+    queues: {
+      title: "Job Queues",
+      pause: "Pause",
+      resume: "Resume",
+      paused_badge: "Paused",
+      retry: "Retry",
+      remove: "Remove",
+      retry_success: "Job retried",
+      retry_error: "Failed to retry job",
+      remove_success: "Job removed",
+      remove_error: "Failed to remove job",
+      pause_success: "Queue paused",
+      pause_error: "Failed to pause queue",
+      resume_success: "Queue resumed",
+      resume_error: "Failed to resume queue",
+      col_id: "ID",
+      col_name: "Name",
+      col_status: "Status",
+      col_attempts: "Attempts",
+      col_created: "Created",
+      col_actions: "Actions",
+      no_jobs: "No jobs found",
+      status_all: "All",
+      status_waiting: "Waiting",
+      status_active: "Active",
+      status_completed: "Completed",
+      status_failed: "Failed",
+      status_delayed: "Delayed",
+      failed_reason: "Reason: {reason}",
+    },
     article_form: {
       new_title: "New article",
       edit_title: "Edit article",