내부 설정 Gemini API 키 입력 문제 수정

- AX Agent 내부 설정 공통 탭의 서비스 API 키 입력 필드를 PasswordBox에서 TextBox로 변경

- Gemini/Claude 키 입력 시 오버레이 동기화 중에도 입력이 끊기지 않도록 보완

- 검증: dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify\\ -p:IntermediateOutputPath=obj\\verify\\ (경고 0 / 오류 0)

src/AxCopilot/Views/ChatWindow.xaml

@@ -3186,13 +3186,14 @@
                                                                Margin="0,4,0,6"
                                                                FontSize="11"
                                                                Foreground="{DynamicResource SecondaryText}"/>
-                                                    <PasswordBox x:Name="TxtOverlayServiceApiKey"
-                                                                 LostFocus="TxtOverlayServiceApiKey_LostFocus"
-                                                                 Padding="9,7"
-                                                                 Background="{DynamicResource LauncherBackground}"
-                                                                 BorderBrush="{DynamicResource BorderColor}"
-                                                                 BorderThickness="1"
-                                                                 FontSize="12"/>
+                                                    <TextBox x:Name="TxtOverlayServiceApiKey"
+                                                             LostFocus="TxtOverlayServiceApiKey_LostFocus"
+                                                             Padding="9,7"
+                                                             Background="{DynamicResource LauncherBackground}"
+                                                             BorderBrush="{DynamicResource BorderColor}"
+                                                             BorderThickness="1"
+                                                             Foreground="{DynamicResource PrimaryText}"
+                                                             FontSize="12"/>
                                                 </StackPanel>
                                             </Grid>
                                         </StackPanel>

src/AxCopilot/Views/ChatWindow.xaml.cs

@@ -10312,7 +10312,7 @@ public partial class ChatWindow : Window
                 if (TxtOverlayServiceEndpoint != null)
                     TxtOverlayServiceEndpoint.Text = GetOverlayServiceEndpoint(service);
                 if (TxtOverlayServiceApiKey != null)
-                    TxtOverlayServiceApiKey.Password = GetOverlayServiceApiKey(service);
+                    TxtOverlayServiceApiKey.Text = GetOverlayServiceApiKey(service);
                 if (TxtOverlayContextCompactTriggerPercent != null)
                     TxtOverlayContextCompactTriggerPercent.Text = Math.Clamp(llm.ContextCompactTriggerPercent, 10, 95).ToString();
                 if (TxtOverlayMaxContextTokens != null)
@@ -10460,7 +10460,7 @@ public partial class ChatWindow : Window
     private void CommitOverlayApiKeyInput()
     {
         var service = NormalizeOverlayService(_settings.Settings.Llm.Service);
-        var apiKey = TxtOverlayServiceApiKey?.Password ?? "";
+        var apiKey = TxtOverlayServiceApiKey?.Text ?? "";
         switch (service)
         {
             case "ollama":