feat: implement dynamic server list loading from API

Add internal/api package to fetch server list from /api/servers.json endpoint

Replace hardcoded server list with dynamic API call

Implement loading states, error handling, and refresh capability

internal/ui/screens/screens.go

@@ -28,27 +28,54 @@ func MainScreen(
 	serverList []Modpack,
 	onPlay func(),
 	onSettings func(),
+	onServerListRefresh func(),
+	isServerListLoading bool,
+	serverListError error,
 ) fyne.CanvasObject {
 
 	// ── Sidebar (Left) ──────────────────────────────────────
-	serverLabels := make([]*widget.Label, len(serverList))
-	serverContainer := container.NewVBox()
+	var sidebar fyne.CanvasObject
+	if isServerListLoading {
+		// Show loading state
+		loadingLabel := widget.NewLabelWithStyle("Loading server list...", fyne.TextAlignCenter, fyne.TextStyle{})
+		sidebar = container.NewVScroll(container.NewVBox(loadingLabel))
+	} else if len(serverList) == 0 && serverListError == nil {
+		// Show empty state (no error, just empty list)
+		emptyLabel := widget.NewLabelWithStyle("No servers available", fyne.TextAlignCenter, fyne.TextStyle{})
+		sidebar = container.NewVScroll(container.NewVBox(emptyLabel))
+	} else if serverListError != nil {
+		// Show error state
+		errorLabel := widget.NewLabelWithStyle("Failed to load server list", fyne.TextAlignCenter, fyne.TextStyle{})
+		detailLabel := widget.NewLabel(serverListError.Error())
+		detailLabel.Wrapping = fyne.TextWrapWord
+		retryBtn := components.SettingsButton(onServerListRefresh)
+		retryBtn.Text = "Retry"
+		sidebar = container.NewVScroll(container.NewVBox(
+			errorLabel,
+			detailLabel,
+			retryBtn,
+		))
+	} else {
+		// Show normal server list
+		serverLabels := make([]*widget.Label, len(serverList))
+		serverContainer := container.NewVBox()
 
-	for i, sp := range serverList {
-		label := widget.NewLabel(sp.Name)
-		serverLabels[i] = label
-		index := i
-		card := components.ServerCard(sp.Name, index == 0, func() {
-			for j, l := range serverLabels {
-				l.TextStyle.Bold = (j == index)
-				l.Refresh()
-			}
-		})
-		serverContainer.Add(card)
+		for i, sp := range serverList {
+			label := widget.NewLabel(sp.Name)
+			serverLabels[i] = label
+			index := i
+			card := components.ServerCard(sp.Name, index == 0, func() {
+				for j, l := range serverLabels {
+					l.TextStyle.Bold = (j == index)
+					l.Refresh()
+				}
+			})
+			serverContainer.Add(card)
+		}
+
+		sidebar = container.NewVScroll(serverContainer)
 	}
 
-	sidebar := container.NewVScroll(serverContainer)
-
 	// ── Center (background + info) ──────────────────────────
 	bg := widget.NewRichTextFromMarkdown(
 		"# Welcome to MrixsCraft\n\n" +
@@ -93,9 +120,14 @@ func MainScreen(
 	playBtn := components.PlayButton(onPlay)
 	settingsBtn := components.SettingsButton(onSettings)
 
+	// Refresh button for server list
+	refreshBtn := components.SettingsButton(onServerListRefresh)
+
 	bottomRight := container.NewHBox(
 		settingsBtn,
 		widget.NewSeparator(),
+		refreshBtn,
+		widget.NewSeparator(),
 		playBtn,
 	)