fix: protect token rotation and account runtime state

[LeaningLearner]

Summary

• Serialize account read-modify-write operations while retaining per-account refresh locking.
• Reconcile active auth.json credentials, stop unsafe refresh rotation while Codex is running, and mark stable refresh failures for re-authentication.
• Add in-place OAuth re-authentication with identity checks and preserve local account settings.
• Keep Codex running state global and restore switch/re-auth confirmation flows.
• Add an English/Chinese UI language switch with a shared locale context, and apply the selected locale consistently to UI copy plus date and time formatting.
• Clean up account menu and sort labels by removing duplicate plus signs and leading percent markers.
• Add compatibility handling and regression tests for legacy account data, concurrent refreshes, re-authentication, runtime state, and date formatting.

Validation

pm run buildn- pm run test:frontendn- cargo test --manifest-path src-tauri/Cargo.toml`n
The local-only packaging override used for the Windows installer is intentionally excluded from this PR. No credentials or machine-specific account data are included.