[codex] improve desktop onboarding status UI

[IchenDEV]

Summary

• Add a dedicated desktop onboarding flow with setup progress, next-step actions, and access path guidance.
• Add a macOS menu bar status panel for sync readiness, account state, active mounts, Finder domain state, refresh, setup, config, and app launch actions.
• Polish dashboard cards, buttons, badges, sidebar rows, and fix Swift JSON decoding for CLI health output.

Validation

• swift build --package-path apps/LarkFSDesktop
• ./script/build_and_run.sh --verify
• go test ./...

Notes

• script/generate_app_icon.swift was already untracked and is not included in this PR.