feat(mosstank): add VTank-style automation PoC

src/AcDream.App/UI/UiField.cs

@@ -110,6 +110,13 @@ public sealed class UiField : UiElement
     public Action<string>? OnSubmit { get; set; }
     public Action? OnFocusGained { get; set; }
     public Action<string>? OnFocusLost { get; set; }
+    /// <summary>
+    /// Live text mutation callback used by retained plugin markup.  This is
+    /// deliberately separate from submit/focus-loss: editors need their
+    /// binding model to track typing so an adjacent button can consume the
+    /// current value without reaching into the widget tree.
+    /// </summary>
+    public Action<string>? OnTextChanged { get; set; }
 
     private string _textValue = "";
 
@@ -127,8 +134,11 @@ public sealed class UiField : UiElement
         get => _textValue;
         set
         {
+            if (string.Equals(_textValue, value, StringComparison.Ordinal))
+                return;
             _textValue = value;
             _textVersion++;
+            OnTextChanged?.Invoke(value);
         }
     }