토큰 카드와 전송 버튼 외곽선 정리

- AX Agent 입력 영역의 토큰 사용량 원형 카드 크기와 내부 링 두께를 재조정
- 토큰 카드 임계점 마커와 퍼센트 텍스트를 축소해 외곽선이 덜 답답하게 보이도록 보정
- 전송 버튼의 불필요한 외곽 테두리를 제거하고 화살표 정렬을 중앙 기준으로 정리
- README와 DEVELOPMENT 문서에 버튼/토큰 UI 미세 조정 이력 추가
- 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

@@ -349,9 +349,10 @@
                     <ControlTemplate TargetType="Button">
                         <Border x:Name="Bd"
                                 Background="#121212"
-                                BorderBrush="#121212"
-                                BorderThickness="1"
-                                CornerRadius="18">
+                                BorderBrush="Transparent"
+                                BorderThickness="0"
+                                CornerRadius="18"
+                                SnapsToDevicePixels="True">
                             <ContentPresenter HorizontalAlignment="Center"
                                               VerticalAlignment="Center"/>
                         </Border>
@@ -1849,36 +1850,37 @@
                                     <Border x:Name="TokenUsageCard"
                                             Grid.Column="2"
                                             Margin="6,0,0,0"
-                                            Padding="1"
-                                            Width="30"
-                                            Height="30"
+                                            Padding="0"
+                                            Width="32"
+                                            Height="32"
                                             CornerRadius="999"
                                             BorderBrush="{DynamicResource BorderColor}"
                                             BorderThickness="1"
                                             Background="{DynamicResource LauncherBackground}"
+                                            SnapsToDevicePixels="True"
                                             VerticalAlignment="Center"
                                             Visibility="Collapsed"
                                             Cursor="Hand"
                                             MouseEnter="TokenUsageCard_MouseEnter"
                                             MouseLeave="TokenUsageCard_MouseLeave">
                                         <Grid>
-                                                <Grid Width="28" Height="28" VerticalAlignment="Center" HorizontalAlignment="Center">
+                                                <Grid Width="24" Height="24" VerticalAlignment="Center" HorizontalAlignment="Center">
                                                 <Ellipse Stroke="{DynamicResource BorderColor}"
-                                                         StrokeThickness="2.5"/>
+                                                         StrokeThickness="1.75"/>
                                                 <Path x:Name="TokenUsageArc"
                                                       Stroke="{DynamicResource AccentColor}"
-                                                      StrokeThickness="3"
+                                                      StrokeThickness="2.25"
                                                       StrokeStartLineCap="Round"
                                                       StrokeEndLineCap="Round"/>
                                                 <Canvas IsHitTestVisible="False">
                                                     <Ellipse x:Name="TokenUsageThresholdMarker"
-                                                             Width="5"
-                                                             Height="5"
+                                                             Width="4"
+                                                             Height="4"
                                                              Fill="{DynamicResource AccentColor}"/>
                                                 </Canvas>
                                                 <TextBlock x:Name="TokenUsagePercentText"
                                                            Text="0%"
-                                                           FontSize="8.25"
+                                                           FontSize="7.5"
                                                            FontWeight="SemiBold"
                                                            Foreground="{DynamicResource PrimaryText}"
                                                            HorizontalAlignment="Center"
@@ -2214,12 +2216,11 @@
                                             VerticalAlignment="Bottom">
                                         <Grid HorizontalAlignment="Center" VerticalAlignment="Center">
                                             <TextBlock Text="↑"
-                                                       FontSize="19"
+                                                       FontSize="18"
                                                        FontWeight="SemiBold"
                                                        Foreground="White"
                                                        HorizontalAlignment="Center"
-                                                       VerticalAlignment="Center"
-                                                       Margin="0,-2,0,0"/>
+                                                       VerticalAlignment="Center"/>
                                         </Grid>
                                     </Button>
                                 </Grid>