Thoth Metrics: canonical ingestion, Sphinx orchestration and client cutover

[ja573]

Objective

Make Thoth the canonical datastore and API for usage and sales metrics, with restartable Sphinx collection, publisher imports, coverage-aware rollups, protected dashboard/widget queries, OPERAS synchronization and reconciled historical migration.

Immutable authority at foundation review head

• Private approved design - Drive revision 6
• Private design reference metadata
• Programme README
• Task tracker
• Source inventory
• Contract register
• Migration inventory
• Acceptance matrix
• Rollout plan
• Foundation specification
• Foundation implementation report
• Foundation PR #764

The Metrics design uses repository-local feature/metrics integration branches only after each repository's branch-readiness gate.

Current gate

• MET-CTRL-01 independently approved and merged
• ADR-0001 approved
• ADR-0002 approved
• BR-SPHINX-01 complete
• SPHINX-BOOT-01 complete
• THOTH-DB-CTRL-01 complete
• client repository branch-readiness decisions recorded
• service-role codes approved before WP5

Work packages

• WP1 - Metrics domain and database foundation
• WP2 - Canonical ingestion service
• WP3 - Import upload and thoth-app experience
• WP4 - Rollups and dashboard GraphQL
• WP5 - Service authentication and entitlements
• WP6 - Sphinx core
• WP7 - CloudFront driver
• WP8 - Additional platform drivers and COUNTER
• WP9 - OPERAS adapter and reconciliation
• WP10 - Dashboard and widget clients
• WP11 - Deployment, monitoring and migration
• MET-E2E-01 - Integrated acceptance and cutover

Do not close at code completion or CI success. Close only after independent approval, merge, required rollout, reconciliation and tracker update.