feat(tasks): Refactor task workflow with payload/refresh separation

Major changes:
- Split crawl into payload_fetch (API → disk) and product_refresh (disk → DB)
- Add task chaining: store_discovery → product_discovery → payload_fetch → product_refresh
- Add payload storage utilities for gzipped JSON on filesystem
- Add /api/payloads endpoints for payload access and diffing
- Add DB-driven TaskScheduler with schedule persistence
- Track newDispensaryIds through discovery promotion for chaining
- Add stealth improvements: HTTP fingerprinting, proxy rotation enhancements
- Add Workers dashboard K8s scaling controls

New files:
- src/tasks/handlers/payload-fetch.ts - Fetches from API, saves to disk
- src/services/task-scheduler.ts - DB-driven schedule management
- src/utils/payload-storage.ts - Payload save/load utilities
- src/routes/payloads.ts - Payload API endpoints
- src/services/http-fingerprint.ts - Browser fingerprint generation
- docs/TASK_WORKFLOW_2024-12-10.md - Complete workflow documentation

Migrations:
- 078: Proxy consecutive 403 tracking
- 079: task_schedules table
- 080: raw_crawl_payloads table
- 081: payload column and last_fetch_at

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/package.json

@@ -22,6 +22,7 @@
     "seed:dt:cities:bulk": "tsx src/scripts/seed-dt-cities-bulk.ts"
   },
   "dependencies": {
+    "@kubernetes/client-node": "^1.4.0",
     "@types/bcryptjs": "^3.0.0",
     "axios": "^1.6.2",
     "bcrypt": "^5.1.1",
@@ -48,6 +49,7 @@
     "puppeteer-extra-plugin-stealth": "^2.11.2",
     "sharp": "^0.32.0",
     "socks-proxy-agent": "^8.0.2",
+    "user-agents": "^1.1.669",
     "uuid": "^9.0.1",
     "zod": "^3.22.4"
   },