feat(remote): add ConnectionSheet for discovering and connecting to hosts

Music/Views/ConnectionSheet.swift

@@ -0,0 +1,65 @@
+import SwiftUI
+import Network
+
+struct ConnectionSheet: View {
+    var remoteClient: RemoteClient
+    @Binding var isPresented: Bool
+
+    var body: some View {
+        VStack(spacing: 16) {
+            Text("Connect to Host")
+                .font(.headline)
+
+            if let message = remoteClient.connectionState.userMessage {
+                HStack(spacing: 8) {
+                    if !remoteClient.connectionState.isConnected &&
+                        remoteClient.connectionState != .disconnected {
+                        ProgressView().controlSize(.small)
+                    }
+                    Text(message)
+                        .font(.subheadline)
+                        .foregroundStyle(.secondary)
+                }
+            }
+
+            if case .connectionLost(let reason) = remoteClient.connectionState {
+                VStack(spacing: 8) {
+                    Text(reason).font(.caption).foregroundStyle(.red)
+                    Button("Retry") { remoteClient.startDiscovery() }
+                }
+            }
+
+            if remoteClient.discoveredHosts.isEmpty && remoteClient.connectionState == .discovering {
+                VStack(spacing: 8) {
+                    ProgressView()
+                    Text("Looking for hosts on your network...")
+                        .font(.caption).foregroundStyle(.secondary)
+                }
+                .frame(height: 100)
+            } else {
+                List(remoteClient.discoveredHosts, id: \.name) { host in
+                    HStack {
+                        Image(systemName: "desktopcomputer").foregroundStyle(.secondary)
+                        Text(host.name)
+                        Spacer()
+                        Button("Connect") { remoteClient.connect(to: host) }
+                            .buttonStyle(.borderedProminent).controlSize(.small)
+                    }
+                    .padding(.vertical, 4)
+                }
+                .frame(minHeight: 100, maxHeight: 200)
+            }
+
+            Button("Cancel") {
+                remoteClient.stopDiscovery()
+                isPresented = false
+            }
+            .keyboardShortcut(.cancelAction)
+        }
+        .padding(20)
+        .frame(width: 380)
+        .onChange(of: remoteClient.connectionState) { _, newState in
+            if case .connected = newState { isPresented = false }
+        }
+    }
+}