style: add Forest Teal accent resources and force dark theme

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ClaudeDo.App/App.axaml

@@ -2,13 +2,37 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              x:Class="ClaudeDo.App.App"
              xmlns:local="using:ClaudeDo.App"
-             RequestedThemeVariant="Default">
-             <!-- "Default" ThemeVariant follows system theme variant. "Dark" or "Light" are other available options. -->
+             RequestedThemeVariant="Dark">
+
+    <Application.Resources>
+        <!-- Accent: Forest Teal -->
+        <SolidColorBrush x:Key="AccentBrush" Color="#3d9474"/>
+        <SolidColorBrush x:Key="AccentLightBrush" Color="#6bb89e"/>
+        <SolidColorBrush x:Key="AccentSubtleBrush" Color="#1A3D9474"/>
+        <SolidColorBrush x:Key="AccentSelectedBrush" Color="#263D9474"/>
+
+        <!-- Text -->
+        <SolidColorBrush x:Key="TextPrimaryBrush" Color="#e2e8f0"/>
+        <SolidColorBrush x:Key="TextSecondaryBrush" Color="#94a3b8"/>
+        <SolidColorBrush x:Key="TextMutedBrush" Color="#5a6578"/>
+        <SolidColorBrush x:Key="TextDimBrush" Color="#475569"/>
+
+        <!-- Borders & Backgrounds -->
+        <SolidColorBrush x:Key="BorderSubtleBrush" Color="#3a4560"/>
+        <SolidColorBrush x:Key="SidebarBgBrush" Color="#1a1a2e"/>
+        <SolidColorBrush x:Key="ContentBgBrush" Color="#16162a"/>
+
+        <!-- Status colors (for checkboxes) -->
+        <SolidColorBrush x:Key="StatusGrayBrush" Color="#475569"/>
+        <SolidColorBrush x:Key="StatusOrangeBrush" Color="#e67e22"/>
+        <SolidColorBrush x:Key="StatusGreenBrush" Color="#3d9474"/>
+        <SolidColorBrush x:Key="StatusRedBrush" Color="#ef4444"/>
+    </Application.Resources>
 
     <Application.DataTemplates>
         <local:ViewLocator/>
     </Application.DataTemplates>
-  
+
     <Application.Styles>
         <FluentTheme />
     </Application.Styles>