feat: rewrite to stateless web app with IndexedDB frontend

Replace CLI + SQLite architecture with a Go web server + vanilla JS
frontend using IndexedDB for all client-side data storage.

- Remove: cli, store, report, static packages
- Add: compute engine (BuildDashboard), server package, web UI
- Add: setup page with CRUD for profiles, rooms, devices, occupants, AC
- Add: dashboard with SVG temperature timeline, risk analysis, care checklist
- Add: i18n support (English/German) with server-side Go templates
- Add: LLM provider selection UI with client-side API key storage
- Add: per-room indoor temperature, edit buttons, language-aware AI summary

tailwind/input.css

@@ -1,3 +1,2 @@
 @import "tailwindcss";
-@source "../internal/report/templates/*.tmpl";
-@source "../internal/cli/templates/*.tmpl";
+@source "../web/**/*.{html,js}";