fix(sidebar): clip dev branch name in title bar

[frenchie4111]

Summary

• In dev mode the sidebar title bar shows `Harness ()`. With a narrow sidebar + long branch name (e.g. `fix-hydrate-remote-backend-poisons-active`), the branch ran off the right edge of the sidebar.
• Add `right-2 overflow-hidden text-ellipsis` to the absolute-positioned title span so it now clips/truncates cleanly within the sidebar bounds.

Test plan

• `npm run typecheck` clean
• `npx electron-vite build` clean
• Visually confirm in dev with a long branch name at narrow sidebar width — "Harness" stays visible to the left of the traffic-light gap and the branch name gets clipped with an ellipsis inside the sidebar.