Add UI sync status indicator with pending badge

- Create htmx-powered partial template for sync status display
- Show Online/Offline indicator with color coding (green/red)
- Display pending changes count badge when there are unsynced items
- Add Sync button to push pending changes (appears only when needed)
- Auto-refresh every 30 seconds via htmx polling
- Replace JavaScript-based sync indicator with server-rendered partial
- Integrate SyncStatusPartial handler with template rendering

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

cmd/server/main.go

@@ -331,7 +331,10 @@ func setupRouter(db *gorm.DB, cfg *config.Config, local *localdb.LocalDB, dbUser
 	exportHandler := handlers.NewExportHandler(exportService, configService, componentService)
 	pricingHandler := handlers.NewPricingHandler(db, pricingService, alertService, componentRepo, priceRepo, statsRepo)
 	pricelistHandler := handlers.NewPricelistHandler(pricelistService, local)
-	syncHandler := handlers.NewSyncHandler(local, syncService, db)
+	syncHandler, err := handlers.NewSyncHandler(local, syncService, db, "web/templates")
+	if err != nil {
+		return nil, nil, fmt.Errorf("creating sync handler: %w", err)
+	}
 
 	// Setup handler (for reconfiguration)
 	setupHandler, err := handlers.NewSetupHandler(local, "web/templates")
@@ -418,6 +421,7 @@ func setupRouter(db *gorm.DB, cfg *config.Config, local *localdb.LocalDB, dbUser
 	partials := router.Group("/partials")
 	{
 		partials.GET("/components", webHandler.ComponentsPartial)
+		partials.GET("/sync-status", syncHandler.SyncStatusPartial)
 	}
 
 	// API routes