- Add Alpine.store('theme') for Light/Dark/System cycling with localStorage persistence
- Add Alpine.store('i18n') with FR/EN translations for all static UI strings
- Add topbar with theme toggle button (:aria-label, @click cycle) and lang button
- Wrap main content in .main-wrapper + .topbar for layout structure
- Add .main-wrapper, .topbar, .topbar-controls styles to app.css
- Add test_theme_toggle_present integration test
- Fix test_dashboard_shows_recent_printers assertion (string now in i18n JS too)
- requirements-dev.txt with pytest and httpx
- tests/conftest.py: client and tmp_data_dir fixtures
- tests/test_health.py: GET /health returns 200 with {"status": "ok"}
- tests/test_static.py: no CDN URLs in templates, dashboard returns 200
- Fix imptune/api/pages.py: use request= kwarg in TemplateResponse (Starlette compat)
- Fix imptune/main.py: replace deprecated on_event with asynccontextmanager lifespan