fix(rankings): rank only providers from the documented free-model catalog

[maxmad64bis]

⚠️ base-red inherited: #15306

Summary

Before, the free ranking listed every provider carrying the static free flag, so entries with no documented free model still showed up while some documented catalog entries stayed out. The cause was two lists using different rules, with the flag alone deciding the ranking instead of the documented catalog. After, the ranking follows the documented free-model catalog, so both surfaces agree and only providers with a documented free grant are listed.

Related Issues

• No linked issue — found while comparing the ranking flag with the documented free-model catalog.

Validation

• Change type: provider
• Focused tests and category gates from the golden path
• npm run lint — ESLint on the touched files is clean; the full run is red on the base (🔴 Release branch not green: release/v3.8.52 #15306).
• Reconciled with the current active release base; focused checks rerun afterward
• Production-code changes include a new or updated automated test in this PR

Tests Added Or Updated

• tests/unit/free-provider-rankings-catalog-unification.test.ts — excludes providers with only the static flag, keeps catalog providers with the flag off, and still lists the always-free case.

Coverage Notes

• src/lib/freeProviderRankings.ts — covered by tests/unit/free-provider-rankings-catalog-unification.test.ts.

Reviewer Notes

• Behavior: Before, any OAuth or API key entry with the static free flag entered the ranking; after, only entries from the documented free-model catalog enter, so flag-only entries leave and catalog entries join. No migration is needed since the ranking is computed at request time. Catalog entries reachable only through web-cookie sign-in stay outside the ranking because the ranking only walks the three supported auth kinds. This keeps the current page categories unchanged and can be revisited if those kinds are ever listed.