feat(branding): add app and installer icons

- app: ClaudeTask.ico wired as ApplicationIcon and MainWindow.Icon
  via avares URI
- installer: ClaudeTaskSetup.ico wired as ApplicationIcon and embedded
  as a WPF Resource so WizardWindow and SettingsWindow can reference it
  via pack URI

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

src/ClaudeDo.Installer/ClaudeDo.Installer.csproj

@@ -8,8 +8,14 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <!-- Allow Linux Gitea runners to publish this WPF project for win-x64; no-op on Windows. -->
     <EnableWindowsTargeting>true</EnableWindowsTargeting>
+    <ApplicationIcon>ClaudeTaskSetup.ico</ApplicationIcon>
   </PropertyGroup>
 
+  <ItemGroup>
+    <!-- Embed icon so it is available via pack URI in WPF windows. -->
+    <Resource Include="ClaudeTaskSetup.ico" />
+  </ItemGroup>
+
   <!-- Debug: asInvoker so Rider/VS can debug without elevation -->
   <PropertyGroup Condition="'$(Configuration)' == 'Debug'">
     <ApplicationManifest>app.debug.manifest</ApplicationManifest>