Support Apple Remote Desktop auth via account username+password

RoyalVNCKit prioritizes .diffieHellman (ARD) over .vnc during handshake when
both are offered. My delegate adapter was passing an empty username to
VNCUsernamePasswordCredential, so any Mac with user-account screen sharing
enabled rejected the credential before .vnc fallback could happen.

Fix: persist a username on SavedConnection and pipe it through to the
credential callback. Leave blank to use the VNC-only password path.

AddConnection footer now explains the two Mac paths:
  • User account (ARD) — macOS short name + full account password
  • VNC-only password — blank username + ≤8 char password

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Packages/VNCUI/Sources/VNCUI/Edit/AddConnectionView.swift

@@ -24,6 +24,7 @@ public struct AddConnectionView: View {
     @State private var displayName = ""
     @State private var host = ""
     @State private var port = "5900"
+    @State private var username = ""
     @State private var password = ""
     @State private var revealPassword = false
     @State private var colorTag: ColorTag = .blue
@@ -45,6 +46,17 @@ public struct AddConnectionView: View {
         !host.trimmingCharacters(in: .whitespaces).isEmpty
     }
 
+    private var authFooterText: String {
+        if isEditing {
+            return "Leave password blank to keep the current one. Stored in iOS Keychain (this device only)."
+        }
+        return """
+        Two Mac paths:
+        • User account (ARD) — enter your macOS short name + full account password. No length limit. Enabled in System Settings → Sharing → Screen Sharing → Allow access for…
+        • VNC-only password — leave the username blank; macOS truncates to 8 characters. Enabled via Screen Sharing → ⓘ → "VNC viewers may control screen with password".
+        """
+    }
+
     public var body: some View {
         NavigationStack {
             Form {
@@ -75,12 +87,17 @@ public struct AddConnectionView: View {
                 }
 
                 Section {
+                    TextField("Username (optional)", text: $username)
+                        #if os(iOS)
+                        .textInputAutocapitalization(.never)
+                        #endif
+                        .autocorrectionDisabled()
                     HStack {
                         Group {
                             if revealPassword {
-                                TextField("VNC password", text: $password)
+                                TextField("Password", text: $password)
                             } else {
-                                SecureField(isEditing ? "Replace password" : "VNC password",
+                                SecureField(isEditing ? "Replace password" : "Password",
                                             text: $password)
                             }
                         }
@@ -96,9 +113,7 @@ public struct AddConnectionView: View {
                 } header: {
                     Text("Authentication")
                 } footer: {
-                    Text(isEditing
-                         ? "Leave blank to keep the current password. Stored in iOS Keychain (this device only)."
-                         : "macOS Screen Sharing's VNC password is limited to 8 characters. Stored in iOS Keychain (this device only).")
+                    Text(authFooterText)
                 }
 
                 Section {
@@ -199,6 +214,7 @@ public struct AddConnectionView: View {
             displayName = existing.displayName
             host = existing.host
             port = String(existing.port)
+            username = existing.username
             colorTag = existing.colorTag
             quality = existing.quality
             inputMode = existing.inputMode
@@ -214,10 +230,12 @@ public struct AddConnectionView: View {
 
     private func save() {
         let portInt = Int(port) ?? 5900
+        let trimmedUsername = username.trimmingCharacters(in: .whitespaces)
         if let existing = editing {
             existing.displayName = displayName
             existing.host = host
             existing.port = portInt
+            existing.username = trimmedUsername
             existing.colorTag = colorTag
             existing.quality = quality
             existing.inputMode = inputMode
@@ -232,6 +250,7 @@ public struct AddConnectionView: View {
                 displayName: displayName,
                 host: host,
                 port: portInt,
+                username: trimmedUsername,
                 colorTag: colorTag,
                 quality: quality,
                 inputMode: inputMode,