[Refactor] Roll out stream helpers to base OpenAI specs

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Created by Roomote. Follow up by mentioning @roomote, in the web UI, or in Discord.

What changed

• Refactored base-openai-compatible-provider.spec.ts to replace custom async-iterator mock objects with asyncStreamFrom and pure collect loops with collectStream.
• Refactored openai-usage-tracking.spec.ts to use the same shared helpers and adjusted the final usage assertion to stay type-safe on the chunk union.
• Removed the stale openai-usage-tracking.spec.ts ESLint suppressions entry after its explicit-any suppressions dropped to zero.

Why this change was made

This continues the approved test-utils rollout with another multi-file batch. openai.spec.ts was intentionally deferred as a larger standalone follow-up so this batch stays reviewable.

Impact

No user-facing behavior change. Two more provider specs use the shared stream-helper idiom, targeted tests passed, src lint/typecheck passed, and the full Zoo-Code test suite passed.

Related PRs

• Async-stream test-utils pilot: [Refactor] Pilot shared stream test utilities #1086
• Requesty stream-helper rollout: [Refactor] Roll out stream helpers to Requesty spec #1089
• Unbound stream-helper rollout: [Refactor] Roll out stream helpers to Unbound spec #1090
• OpenAI-family stream-helper batch: [Refactor] Batch roll out stream helpers to OpenAI-family specs #1091

[zoomote]

No code issues found. See task

Review summary

The refactor is a faithful mechanical swap of custom async-iterator mocks for asyncStreamFrom and manual collect loops for collectStream across both specs. Verified in context:

• asyncStreamFrom returns an AsyncGenerator, which is itself async-iterable, so it is a drop-in replacement for the previous [Symbol.asyncIterator] mock objects; each stream is consumed exactly once per test, so the single-use nature of generators is not an issue.
• All chunk sequences, expected outputs, and assertions are preserved 1:1, including tool-call, reasoning-tag, and usage-tracking cases. The toMatchObject change on the final usage assertion in openai-usage-tracking.spec.ts is equivalent in coverage.
• The removed ESLint suppression entry for openai-usage-tracking.spec.ts is correct: the file no longer contains any explicit any. The remaining base-openai-compatible-provider.spec.ts suppression (count 1) still matches the pre-existing (c: any) on line 375.
• Verified locally: both specs pass (18 tests) and eslint --prune-suppressions --max-warnings=0 passes on both files.

_{Reviewed 58d38c7}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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