Phase 1: Database migrations for platform features

Migrations created:
- 001_add_job_platform_fields.sql: Add 15 new columns to jobs table
  - Requester tracking (client_id, source, purpose, metadata)
  - Batch support (batch_id, batch_index)
  - Execution tracking (job_type, scraper_version, variant, priority)
  - Webhook callbacks (url, status, sent_at, attempts)
  - Result summary (JSONB for cross-type dashboard)
  - 7 indexes for query performance
  - 5 CHECK constraints for data validation

- 002_create_batches_table.sql: Batch job grouping
  - Tracks batch progress (total/completed/failed)
  - Batch-level callbacks
  - Requester association

- 003_create_scraper_registry.sql: Scraper version management
  - Version routing (stable/beta/canary variants)
  - A/B traffic splitting (traffic_pct)
  - Priority-based routing
  - Seeds google_reviews v1.0.0 as stable default

- 004_create_api_keys.sql: API authentication
  - Secure key storage (SHA-256 hashes, not plaintext)
  - Scopes-based permissions
  - Rate limiting support
  - Key lifecycle (expiry, active status)

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

.artifacts/CONTEXT-KEEPER.md

@@ -103,7 +103,7 @@ reviewiq/                          # Will rename from google-reviews-scraper-pro
 
 | Phase | Description | Status |
 |-------|-------------|--------|
-| 0 | Project restructure (move files to new locations) | Not started |
+| 0 | Project restructure (move files to new locations) | ✅ COMPLETE |
 | 1 | Database migrations (new fields + tables) | Not started |
 | 2 | Requester & batch support | Not started |
 | 3 | Webhooks | Not started |