feat: phase 1 MVP — sections, services, drag-drop, renderers

Backend: migration 0002 (sections/items/urls/settings), CRUD +
fractional reorder, icon upload, settings, export/import, cached
status pings. Handler tests cover reorder, URL scheme validation,
settings round-trip.

Frontend: shared board store over the generated client, dnd-kit
layer (same-section, cross-section, section reorder persisted),
URL chooser popover, add/edit service dialog, settings dialog,
Bento + Cards renderers behind the shared seam, dark/light theme.

Generated with [Devin](https://devin.ai)

Authored By: TDvorak <[email protected]>
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/cmd/dash/main.go

@@ -42,7 +42,8 @@ func main() {
 	}
 	defer func() { _ = sqlDB.Close() }()
 
-	router := api.NewRouter(logger, sqlDB)
+	iconsDir := filepath.Join(dataDir, "icons")
+	router := api.NewRouter(logger, sqlDB, iconsDir)
 	if err := web.Register(router); err != nil {
 		logger.Fatal("register embedded UI", zap.Error(err))
 	}