fix: restore rate limit auto refresh

[lynnswap]

Summary

• Add store-owned rate-limit auto refresh scheduling for selected and background accounts, including reset-window refreshes and per-account in-flight deduping.
• Carry account kind and rate-limit capabilities through app-server responses, CodexAccount state, host account snapshots, and the persisted account registry.
• Add focused tests for scheduling policy, unsupported account capabilities, registry kind persistence, and app-server account normalization.

Testing

• swift test --build-system swiftbuild --no-parallel
• xcodebuild test -project Tools/ReviewMonitor/ReviewMonitor.xcodeproj -scheme ReviewMonitor -destination 'platform=macOS,arch=arm64' CODE_SIGNING_ALLOWED=NO CODE_SIGNING_REQUIRED=NO
• codex-review on uncommitted changes: no findings