ALL-1875 PR-2: Scheduled duplicate-detection BullMQ job

## ALL-1875: Contact merge UI + auto duplicate detection — PR 2 of 5 ### Goal Wire the detectDuplicates service (from PR-1) into a scheduled BullMQ job that runs periodically. ### Context - Linear issue: ALL-1875 - Branch: `wilbo/all-1875-duplicate-detection-job` - Worktree: `mono-all-1875-duplicate-detection-job` - Depends on: PR-1 merged (DuplicateCandidate table + detectDuplicates service exist) ### What to build New BullMQ job at `domains/identity/src/jobs/duplicateDetection/`: 1. **`queue.ts`** — `initDuplicateDetectionQueue` / `shutdownDuplicateDetectionQueue` - Queue name: `duplicate-detection` - Use repeatable job with cron pattern defaulting to `0 2 * * *` (2 AM daily) — configurable via env/config 2. **`worker.ts`** — `initDuplicateDetectionWorker` / `shutdownDuplicateDetectionWorker` - Fetch all workspaceIds that have CanonicalContacts (skip empty workspaces) - For each workspace, call `detectDuplicates(workspaceId)` from PR-1 - Emit metrics: candidates_found, candidates_dismissed_total counters - Handle errors per-workspace (log + skip, do not fail the whole job) 3. **Register in `domains/identity/src/jobs/index.ts`**: - Add `initDuplicateDetectionQueue()` + `initDuplicateDetectionWorker()` to `initializeJobs()` - Add corresponding shutdown calls to `shutdownJobs()` ### Key existing files to copy patterns from - `domains/identity/src/jobs/bulkImport/importJob/queue.ts` — BullMQ queue init pattern - `domains/identity/src/jobs/bulkImport/importJob/worker.ts` — BullMQ worker pattern - `domains/identity/src/jobs/index.ts` — where to register - `domains/identity/src/jobs/stagingProfile/` — another good repeatable-job pattern ### Acceptance test - Job appears in BullMQ dashboard when service starts - Worker processes a workspace with known duplicate emails and writes DuplicateCandidate rows - Failed workspace does not halt remaining workspaces - Metrics increment (check Datadog or console logs in dev) ### Depends on - PR-1 merged (fleet-task dd69e15f-601c-468a-a128-9a9bd795e237) ### Out of scope - GraphQL queries for the frontend (PR-3) - Frontend UI (PR-4)