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/backend/src/graphql/resolvers/queues.ts

@@ -0,0 +1,153 @@
+import { GraphQLError } from "graphql";
+import type { Job } from "bullmq";
+import { builder } from "../builder.js";
+import { JobType, QueueInfoType } from "../types/index.js";
+import { queues } from "../../queues/index.js";
+import { requireAdmin } from "../../lib/acl.js";
+
+const JOB_STATUSES = ["waiting", "active", "completed", "failed", "delayed"] as const;
+type JobStatus = (typeof JOB_STATUSES)[number];
+
+async function toJobData(job: Job, queueName: string) {
+  const status = await job.getState();
+  return {
+    id: job.id ?? "",
+    name: job.name,
+    queue: queueName,
+    status,
+    data: job.data as unknown,
+    result: job.returnvalue as unknown,
+    failedReason: job.failedReason ?? null,
+    attemptsMade: job.attemptsMade,
+    createdAt: new Date(job.timestamp),
+    processedAt: job.processedOn ? new Date(job.processedOn) : null,
+    finishedAt: job.finishedOn ? new Date(job.finishedOn) : null,
+    progress: typeof job.progress === "number" ? job.progress : null,
+  };
+}
+
+builder.queryField("adminQueues", (t) =>
+  t.field({
+    type: [QueueInfoType],
+    resolve: async (_root, _args, ctx) => {
+      requireAdmin(ctx);
+      return Promise.all(
+        Object.entries(queues).map(async ([name, queue]) => {
+          const counts = await queue.getJobCounts(
+            "waiting",
+            "active",
+            "completed",
+            "failed",
+            "delayed",
+            "paused",
+          );
+          const isPaused = await queue.isPaused();
+          return {
+            name,
+            counts: {
+              waiting: counts.waiting ?? 0,
+              active: counts.active ?? 0,
+              completed: counts.completed ?? 0,
+              failed: counts.failed ?? 0,
+              delayed: counts.delayed ?? 0,
+              paused: counts.paused ?? 0,
+            },
+            isPaused,
+          };
+        }),
+      );
+    },
+  }),
+);
+
+builder.queryField("adminQueueJobs", (t) =>
+  t.field({
+    type: [JobType],
+    args: {
+      queue: t.arg.string({ required: true }),
+      status: t.arg.string(),
+      limit: t.arg.int(),
+      offset: t.arg.int(),
+    },
+    resolve: async (_root, args, ctx) => {
+      requireAdmin(ctx);
+      const queue = queues[args.queue];
+      if (!queue) throw new GraphQLError(`Queue "${args.queue}" not found`);
+
+      const limit = args.limit ?? 25;
+      const offset = args.offset ?? 0;
+      const statuses: JobStatus[] = args.status
+        ? [args.status as JobStatus]
+        : [...JOB_STATUSES];
+
+      const jobs = await queue.getJobs(statuses, offset, offset + limit - 1);
+      return Promise.all(jobs.map((job) => toJobData(job, args.queue)));
+    },
+  }),
+);
+
+builder.mutationField("adminRetryJob", (t) =>
+  t.field({
+    type: "Boolean",
+    args: {
+      queue: t.arg.string({ required: true }),
+      jobId: t.arg.string({ required: true }),
+    },
+    resolve: async (_root, args, ctx) => {
+      requireAdmin(ctx);
+      const queue = queues[args.queue];
+      if (!queue) throw new GraphQLError(`Queue "${args.queue}" not found`);
+      const job = await queue.getJob(args.jobId);
+      if (!job) throw new GraphQLError(`Job "${args.jobId}" not found`);
+      await job.retry();
+      return true;
+    },
+  }),
+);
+
+builder.mutationField("adminRemoveJob", (t) =>
+  t.field({
+    type: "Boolean",
+    args: {
+      queue: t.arg.string({ required: true }),
+      jobId: t.arg.string({ required: true }),
+    },
+    resolve: async (_root, args, ctx) => {
+      requireAdmin(ctx);
+      const queue = queues[args.queue];
+      if (!queue) throw new GraphQLError(`Queue "${args.queue}" not found`);
+      const job = await queue.getJob(args.jobId);
+      if (!job) throw new GraphQLError(`Job "${args.jobId}" not found`);
+      await job.remove();
+      return true;
+    },
+  }),
+);
+
+builder.mutationField("adminPauseQueue", (t) =>
+  t.field({
+    type: "Boolean",
+    args: { queue: t.arg.string({ required: true }) },
+    resolve: async (_root, args, ctx) => {
+      requireAdmin(ctx);
+      const queue = queues[args.queue];
+      if (!queue) throw new GraphQLError(`Queue "${args.queue}" not found`);
+      await queue.pause();
+      return true;
+    },
+  }),
+);
+
+builder.mutationField("adminResumeQueue", (t) =>
+  t.field({
+    type: "Boolean",
+    args: { queue: t.arg.string({ required: true }) },
+    resolve: async (_root, args, ctx) => {
+      requireAdmin(ctx);
+      const queue = queues[args.queue];
+      if (!queue) throw new GraphQLError(`Queue "${args.queue}" not found`);
+      await queue.resume();
+      return true;
+    },
+  }),
+);