feat(gui): Claude Code workspace view

[Wibias]

Summary

• Add a Claude Code Workspace layout with a section rail (Settings, Get started, Background helper model, Model interception, Available models) driven by the global Classic/Workspace toggle.
• Keep Classic as the existing stacked page; wire viewMode from App like other workspace pages.
• Polish: no duplicate rail title, section content aligned to the Settings card top, vertically centered toggle knobs, and remove the left inset accent bar from shared Select menus.

Test plan

• Open GUI #claude in Classic — page still stacks all sections as before
• Switch to Workspace — rail sections switch the main pane; Settings card top aligns with other sections
• Toggle switches on Claude settings — knobs look vertically centered
• Open any Select (auth mode, sidecar backend, etc.) — no white left edge highlight on focused options
• bun run typecheck / GUI lint if touching further

Summary by CodeRabbit

• New Features

  • Added a workspace view for Claude Code with sidebar navigation and section switching.
  • Added a localized “Settings” label in English, German, Japanese, Korean, Russian, and Chinese.
  • Added responsive layouts for smaller screens.

• Style

  • Improved workspace selection highlights, custom dropdowns, and toggle switch alignment.
  • Refined the combo workspace rail’s selected-state appearance.

[Wibias]

Addressed CodeRabbit review in 411a68a3:

• Workspace-only Settings h-section (Classic unchanged)
• Rail aria-current=\"true\" (matches ComboWorkspace / Usage)
• Selected+keyboard Select cue restored as a full inset ring (no left stripe)