Phase 3: app icon (multi-resolution ICO + master PNG)

scripts/generate-icons.ps1 renders the icon programmatically with
System.Drawing - rounded teal square (#0E7C66) with a stylized white
hook glyph - at 16/24/32/48/64/128/256 px and assembles a proper
multi-resolution Microsoft ICO. The PNG and ICO outputs land in
resources/. The script is the source of truth; re-run after editing
the design.

GUI csproj uses ApplicationIcon for the EXE icon and embeds the .ico
+ .png as Resources so MainWindow and AboutDialog can use them via
WPF's resource URI scheme.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/WebhookServer.Gui/MainWindow.xaml

@@ -7,6 +7,7 @@
         xmlns:models="clr-namespace:WebhookServer.Core.Models;assembly=WebhookServer.Core"
         mc:Ignorable="d"
         Title="Webhook Server" Height="600" Width="1000"
+        Icon="/webhook-server.ico"
         d:DataContext="{d:DesignInstance Type=vm:MainViewModel}">
     <Window.InputBindings>
         <KeyBinding Key="N" Modifiers="Control" Command="{Binding AddEndpointCommand}"/>

src/WebhookServer.Gui/Views/AboutDialog.xaml

@@ -2,9 +2,10 @@
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Title="About Webhook Server"
-        Height="320" Width="420"
+        Height="360" Width="440"
         ResizeMode="NoResize"
         WindowStartupLocation="CenterOwner"
+        Icon="/webhook-server.ico"
         ShowInTaskbar="False">
     <Grid Margin="20">
         <Grid.RowDefinitions>

src/WebhookServer.Gui/WebhookServer.Gui.csproj

@@ -14,6 +14,13 @@
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <UseWPF>true</UseWPF>
+    <ApplicationIcon>..\..\resources\webhook-server.ico</ApplicationIcon>
+    <AssemblyTitle>Webhook Server</AssemblyTitle>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Resource Include="..\..\resources\webhook-server.ico" Link="webhook-server.ico" />
+    <Resource Include="..\..\resources\webhook-server.png" Link="webhook-server.png" />
+  </ItemGroup>
+
 </Project>