feat: query account usage without switching

[SilkageNet]

Summary

• query saved ChatGPT accounts through isolated temporary CODEX_HOME instances and the official Codex App Server
• show rate limits and aggregate token usage in account usage and account list
• cache credential-free snapshots, reconcile refreshed credentials safely, and preserve the active account projection
• document protocol compatibility, security boundaries, and offline behavior

Validation

• go test -race ./...
• go vet ./...
• golangci-lint run
• Linux, Windows, and macOS cross-builds
• gitleaks dir . --redact --no-banner
• queried active and inactive real profiles; inactive query left the active auth.json SHA-256 unchanged