feat(platform): deliver metadata fabric lineage on mainline

[zhouning]

Summary

• add tenant-scoped Metadata Fabric OpenLineage outbox with content-bound enqueue, bounded claim/lease/retry, receipt state, FORCE RLS, and gateway-only mutation functions
• deliver the exact M3-1 candidate gated by the M3-3 binding over a strict loopback HTTP emitter with stable idempotency headers
• preserve local-only claim boundaries: local wire delivery is verified, while live/protected OpenLineage, OIDC, durable catalog, production receiver, production ingestion, and production readiness remain false
• replace historical stacked PR feat(platform): deliver metadata fabric lineage #18 with a main-based implementation and keep CI/staging test inventories aligned

Verification

• Platform Required Tests: 641 passed
• Metadata Fabric focused suite: 49 passed, 2 environment-skipped; both PostgreSQL integration cases separately passed against PostgreSQL 16
• local PostgreSQL + loopback rehearsal: first response 503, retry duplicate 200, 2 requests, 1 unique receiver acceptance, final delivered, completed item not reclaimed
• evidence SHA: 5aabe9950d2d3d0cfb50ee9d9163c8dee60b04e800f68baad5090e97319b5d8d
• Ruff on new/changed M3-4 Python paths, YAML parse, bash syntax, compileall, and diff check passed

Boundaries

No staging or production workflow was triggered. This PR does not prove protected receiver identity/TLS, provider minimum privilege, durable catalog/binding, tenant-isolated production deployment, live OpenLineage, production ingestion, or production readiness.