Yattee v2 rewrite

Yattee/Views/Components/InstanceToolbarButton.swift

@@ -0,0 +1,55 @@
+//
+//  InstanceToolbarButton.swift
+//  Yattee
+//
+//  A toolbar button that shows the current active instance and allows switching.
+//
+
+import SwiftUI
+
+struct InstanceToolbarButton: View {
+    @Environment(\.appEnvironment) private var appEnvironment
+    @State private var showingPicker = false
+
+    var body: some View {
+        if let instancesManager = appEnvironment?.instancesManager,
+           instancesManager.enabledInstances.count > 1 {
+            Button {
+                showingPicker = true
+            } label: {
+                HStack(spacing: 4) {
+                    Image(systemName: iconForInstance)
+                    Text(instancesManager.activeInstance?.displayName ?? "")
+                        .font(.subheadline)
+                        .lineLimit(1)
+                    Image(systemName: "chevron.down")
+                        .font(.caption2)
+                }
+            }
+            .sheet(isPresented: $showingPicker) {
+                InstancePickerSheet()
+            }
+        }
+    }
+
+    private var iconForInstance: String {
+        guard let instance = appEnvironment?.instancesManager.activeInstance else {
+            return "server.rack"
+        }
+        return instance.type.systemImage
+    }
+}
+
+// MARK: - Preview
+
+#Preview {
+    NavigationStack {
+        Text("Content")
+            .toolbar {
+                ToolbarItem(placement: .automatic) {
+                    InstanceToolbarButton()
+                }
+            }
+    }
+    .appEnvironment(.preview)
+}