feat: Stealth worker system with mandatory proxy rotation

## Worker System
- Role-agnostic workers that can handle any task type
- Pod-based architecture with StatefulSet (5-15 pods, 5 workers each)
- Custom pod names (Aethelgard, Xylos, Kryll, etc.)
- Worker registry with friendly names and resource monitoring
- Hub-and-spoke visualization on JobQueue page

## Stealth & Anti-Detection (REQUIRED)
- Proxies are MANDATORY - workers fail to start without active proxies
- CrawlRotator initializes on worker startup
- Loads proxies from `proxies` table
- Auto-rotates proxy + fingerprint on 403 errors
- 12 browser fingerprints (Chrome, Firefox, Safari, Edge)
- Locale/timezone matching for geographic consistency

## Task System
- Renamed product_resync → product_refresh
- Task chaining: store_discovery → entry_point → product_discovery
- Priority-based claiming with FOR UPDATE SKIP LOCKED
- Heartbeat and stale task recovery

## UI Updates
- JobQueue: Pod visualization, resource monitoring on hover
- WorkersDashboard: Simplified worker list
- Removed unused filters from task list

## Other
- IP2Location service for visitor analytics
- Findagram consumer features scaffolding
- Documentation updates

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

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

backend/.gitignore

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+# IP2Location database (downloaded separately)
+data/ip2location/