Make workspace surfaces worktree aware

[Anton-Horn]

Summary

• add independent worktree scopes for file navigation and Source Control changes
• keep repository-wide Source Control operations on the canonical repository while routing checkout-local operations to the selected worktree
• make editor, document, review, terminal, panel inheritance, window sync, and Cate host file routing worktree aware
• persist checkout selections and panel affinity in machine-local session state while keeping workspace state portable
• keep Parallel Work as the dedicated worktree lifecycle and orchestration surface

Validation

• npm run typecheck
• npm run lint (passes with 22 existing warnings)
• npm run build
• 89 focused Vitest tests covering worktree resolution, persistence, autosave, status routing, host actions, Quick Open, and dock actions

The full local suite still has unrelated environment failures involving socket permissions, the Electron binary, native watcher timeouts, and an existing review whitespace assertion.