[Candidate Intake] Upstream PR #224 - feat(api-keys): add per-API-key model allowlist filtering

[nsalvacao]

Context

This draft PR mirrors upstream branch 'upstream-prs/pr-224' into 'master' for review, provenance, and later decision-making only.
It must not be merged wholesale. If we adopt anything from it, the intended path is commit-level intake only.

Upstream Source

• Original PR: feat(api-keys): add per-API-key model allowlist filtering decolua/9router#224
• Original author: @toanalien
• Original title: "feat(api-keys): add per-API-key model allowlist filtering"
• Mirrored branch on this fork: upstream-prs/pr-224
• Current divergence snapshot vs master: 1 commits ahead, 90 commits behind

Current Intake Recommendation

• Decision: Candidate intake
• Status: Planned review only, with no integration performed yet
• Credit policy: preserve original author metadata, use git cherry-pick -x for any later intake, and keep any conflict adaptation in separate follow-up commits with explicit upstream attribution

Selected Commits For Any Future Intake

• 89830a0 feat(api-keys): add per-API-key model allowlist filtering

Skipped / Excluded Scope

• No additional excluded commit set beyond the currently selected scope.

Acceptance Gates

• Do not merge this mirrored branch as-is.
• If anything is adopted later, intake only the explicitly selected commits or a newly re-validated subset.
• Preserve upstream authorship and provenance in Git history.
• Keep conflict-resolution/adaptation commits separate from upstream-authored commits.
• Reconfirm branch contents against current master at intake time before changing the selected scope.

Verification / Validation Checklist

• Keys can store and edit allowedModels safely.
• Requests for disallowed models are rejected with the intended status.
• Existing keys without allowlists remain backward compatible.

Review Focus

• API key schema and storage changes for allowedModels
• Authorization behavior for blocked models
• UI affordance for editing allowlists without breaking existing keys

Notes

• This PR is intentionally draft and exists to support review, provenance, and later commit-level intake decisions.