feat(platform): gate metadata provider identity

[zhouning]

Summary

• add a versioned production Metadata Fabric identity profile and fail-closed profile/attestation/report gate
• bind OpenMetadata 1.13.1 and Gravitino 1.3.0 to the exact M3-5/M3-6 local identity evidence and minimum-privilege contracts
• require explicit OIDC/workload/tenant, digest-pinned provider authentication, TLS/mTLS, persistent catalog, tenant isolation, lifecycle and operational decisions
• add ADR-053, roadmap/System-of-Record updates, CI validation and 26 focused tests

Evidence boundary

• the checked-in profile is structurally valid but exposes 40 external production blockers
• Gravitino 1.3.0 ships the Basic IdP jar only; this gate allows a custom OIDC authenticator or identity-aware proxy and does not invent native OIDC support
• no production identity component is deployed and no real production attestation is committed
• all production identity claims and overall production_ready remain false

Verification

• 26 focused identity-gate tests passed
• platform truth validation passed
• required platform suite: 655 passed
• profile fingerprint: 2e9d5cac3560b853820f923669f6794ead63bcb36a528639fc0e9539e148ee2f
• report fingerprint: c607589ee25a87acc8a1ab71372618a9a4c10c1e8ebff15b8db7e78b37600b9f

Stack

Depends on #20 and targets feat/ar1-metadata-fabric-gravitino-identity. Do not merge this PR before its parent.