Fix all build/type/lint errors, write 46 new tests (222 total across
20 files), regenerate Prisma client, update seed with user preferences.
Fix SvelteSet usage, add {#each} keys, clean unused imports.
- JSON import/export with conflict resolution (skip/overwrite) + admin UI
- Ping history sparklines on AppWidget and AppCard (24h, 288 points)
- Hourly cleanup job for old AppStatus records
- User theme preferences (hue, saturation, mode, background, locale)
- Settings page with ThemeCustomizer (sliders, toggles, live preview)
- Prisma migration for user preference fields
- i18n translations for all new strings (EN/RU)
alexei.dolgolyov