Fix Claude rate-limit handling for mixed account states

[kargnas]

Summary

This change fixes the Claude multi-account menu behavior when one account still has usable quota data but another account is in a rate-limited cooldown window. Users were seeing the entire Claude section collapse into a single Rate limited provider row, which hid both Claude accounts from the dropdown even though one account remained valid and should still have been visible.

The root cause was the provider-level error precedence in the menu renderer. ProviderManager intentionally preserves rate-limit errors during the cooldown interval, even when cached provider results are still available. StatusBarController treated that provider-level rate-limit error as higher priority than the existing multi-account result and replaced the account rows with a single error row. In mixed-account Claude states, that meant an error produced by one account could visually suppress the other account and make the whole provider appear unavailable.

The fix adds a shared display policy for rate-limited rows. Multi-account providers now keep rendering their account rows whenever displayable account data already exists, and the provider-level Rate limited row is only shown when there are no account rows to render. This keeps the existing cooldown behavior for providers that truly have no visible account data, while preserving Claude, Codex, Copilot, and Gemini account rows when cached or current account-level data is still available.

I also added regression coverage for the display policy. The new tests verify that Claude account rows remain visible during a rate-limit cooldown when account data exists, and that single-result providers without account rows still surface the rate-limit error row as before.

Validation

I validated the change with the existing targeted provider regression suite and with a clean local Debug build:

• xcodebuild test -project CopilotMonitor/CopilotMonitor.xcodeproj -scheme CopilotMonitor -configuration Debug -destination 'platform=macOS' -only-testing:CopilotMonitorTests/ProviderUsageTests
• xcodebuild -project CopilotMonitor/CopilotMonitor.xcodeproj -scheme CopilotMonitor -configuration Debug -destination 'platform=macOS' clean build

I also restarted the Debug app and confirmed the updated build launched successfully and emitted provider logs. The exact mixed live state was not reproducible at run time because both Claude accounts were returning HTTP 429 during that launch window, so the final user-facing behavior for the mixed state is covered by the new regression tests.

[op-gg-ai-devops]

Rate Limit 오류가 있어도 표시할 계정 데이터가 있다면 에러 뷰 대신 정보를 우선 보여주도록 ProviderDisplayPolicy를 도입했네.

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ProviderDisplayPolicy로 표시 정책 로직을 분리해 StatusBarController가 스파게티 되는 걸 잘 막았어, 구조적으로 아주 칭찬해. 다만 isRateLimitError에서 매직 스트링("rate limited", "http 429")에 의존하는 방식은 API 메시지가 조금만 바껴도 바로 터질 수 있어서 위험해 보여. 가능하다면 명시적인 에러 코드나 타입으로 판단하도록 개선하는 게 좋겠어. 테스트 케이스도 꼼꼼하게 잘 챙겼네.

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