feat: gamification queue with deduplication and unpublish revoke

- Add migration 0004: partial unique index on user_points (user_id, action, recording_id)
  for RECORDING_CREATE and RECORDING_FEATURED to prevent earn-on-republish farming
- Add revokePoints() to gamification lib; awardPoints() now uses onConflictDoNothing
- Add gamificationQueue (BullMQ) with 3-attempt exponential backoff
- Add gamification worker handling awardPoints, revokePoints, checkAchievements jobs
- Move all inline gamification calls in recordings + comments resolvers to queue
- Revoke RECORDING_CREATE points when a recording is unpublished (published → draft)
- Register gamification worker at server startup alongside mail worker

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

packages/backend/src/queues/workers/gamification.ts

@@ -0,0 +1,49 @@
+import { Worker } from "bullmq";
+import { redisConnectionOpts } from "../connection.js";
+import { awardPoints, revokePoints, checkAchievements } from "../../lib/gamification.js";
+import { db } from "../../db/connection.js";
+import { logger } from "../../lib/logger.js";
+import type { POINT_VALUES } from "../../lib/gamification.js";
+
+const log = logger.child({ component: "gamification-worker" });
+
+export type GamificationJobData =
+  | { job: "awardPoints"; userId: string; action: keyof typeof POINT_VALUES; recordingId?: string }
+  | { job: "revokePoints"; userId: string; action: keyof typeof POINT_VALUES; recordingId: string }
+  | { job: "checkAchievements"; userId: string; category?: string };
+
+export function startGamificationWorker(): Worker {
+  const worker = new Worker(
+    "gamification",
+    async (bullJob) => {
+      const data = bullJob.data as GamificationJobData;
+      log.info({ jobId: bullJob.id, job: data.job, userId: data.userId }, "Processing gamification job");
+
+      switch (data.job) {
+        case "awardPoints":
+          await awardPoints(db, data.userId, data.action, data.recordingId);
+          break;
+        case "revokePoints":
+          await revokePoints(db, data.userId, data.action, data.recordingId);
+          break;
+        case "checkAchievements":
+          await checkAchievements(db, data.userId, data.category);
+          break;
+        default:
+          throw new Error(`Unknown gamification job: ${(data as GamificationJobData).job}`);
+      }
+
+      log.info({ jobId: bullJob.id, job: data.job }, "Gamification job completed");
+    },
+    { connection: redisConnectionOpts },
+  );
+
+  worker.on("failed", (bullJob, err) => {
+    log.error(
+      { jobId: bullJob?.id, job: (bullJob?.data as GamificationJobData)?.job, err: err.message },
+      "Gamification job failed",
+    );
+  });
+
+  return worker;
+}