Remove abuse service from AI gateway paths

[chrarnoldus]

Summary

• remove abuse classification calls and cached rules-engine enforcement from the shared AI gateway route
• remove abuse cost reporting from usage processing
• retain non-gateway auth and lifecycle event reporting plus nullable legacy usage metadata for compatibility

Validation

• pnpm format:changed
• local tests intentionally not run; CI will validate the change

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Executive Summary

This PR cleanly removes the shared AI-gateway abuse classification, quarantine/rules-engine enforcement, and abuse cost reporting; I verified every removed export and field has no remaining references and that the retained provider/route code is internally consistent.

Files Reviewed (9 files)

• apps/web/src/app/api/openrouter/[...path]/route.ts
• apps/web/src/app/api/openrouter/[...path]/route.test.ts
• apps/web/src/lib/ai-gateway/abuse-service.ts
• apps/web/src/lib/ai-gateway/processUsage.ts
• apps/web/src/lib/ai-gateway/processUsage.test.ts
• apps/web/src/lib/ai-gateway/processUsage.types.ts
• apps/web/src/lib/ai-gateway/providers/upstream-attempt.ts
• apps/web/src/lib/proxy-error-types.ts
• apps/web/src/lib/redis-keys.ts

Verified: no remaining references to the removed classifyAbuse/reportAbuseCost/rules-engine helpers or abuseRulesClassificationRedisKey; ProxyErrorType.abuse_blocked and the delayMs propagation are fully removed; effectiveModelIdLowerCased/accessCheckResolver are no longer reassigned so const is correct; remaining abuse_delay/abuse_downgraded_from nulls keep DB compatibility; the updated classifier-billing test matches the 400 returned by apiKindNotSupportedResponse. Tests were not executed (read-only review).

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_{Reviewed by deepseek-v4.1-flash · Input: 0 · Output: 0 · Cached: 0}

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