chore(ai-gateway): prune delisted unavailable models

[chrarnoldus]

Summary

• Remove five explicit unavailable-model entries absent from OpenRouter’s public catalog: three NVIDIA free models, GPT-OSS 20B free, and Tencent Hy3 free.
• Keep the two Gemma 4 free models and GLM 5.2 free blocked because they remain publicly listed.
• Rely on the existing OpenRouter catalog validation for delisted IDs, without changing its behavior or the independent disabled-exclusive check.
• Update unavailable-model fixtures and add regression coverage for the removed entries.

Verification

• Compared exact IDs against https://openrouter.ai/api/v1/models on 2026-08-31 (395 models).
• Passed targeted formatting and git diff --check; reviewed the full diff.
• Tests ran only in CI as requested. CI tests, build, lint, typecheck, formatting, migration checks, extension verification/build/E2E, and secret scanning all passed.
• Kilo Code Review completed with no issues found.
• Local targeted oxlint and pnpm typecheck --changes-only each exceeded the sandbox’s two-minute limit; their CI checks subsequently passed. Local Node is 22.22.3; the repository requires Node 24.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (4 files)

• apps/web/src/lib/ai-gateway/unavailable-models.ts
• apps/web/src/lib/ai-gateway/unavailable-models.test.ts
• apps/web/src/lib/ai-gateway/providers/openrouter/free-endpoint-data-policy.test.ts
• apps/web/src/app/api/openrouter/models/[provider]/[model]/endpoints/route.test.ts

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_{Reviewed by grok-4.6 · Input: 112.9K · Output: 7.7K · Cached: 375.3K}

_{Review guidance: REVIEW.md from base branch main}