Add Windows app icon resource & load it

Add Windows resource files and load the app icon in the window class. Introduce resources/nebula.rc and resources/resource.h (defines IDI_APPICON referencing assets/images/branding/Nebula-Favicon.ico). Include resource.h in nebula_window_win.cpp and set window_class.hIcon/hIconSm via LoadImageW. Update CMakeLists.txt to compile the .rc and add the resources include directory for Windows.

CMakeLists.txt

@@ -60,6 +60,7 @@ if(OS_WINDOWS)
         src/platform/win/startup_win.cpp
         src/platform/win/browser_host_win.cpp
         src/platform/win/nebula_window_win.cpp
+        resources/nebula.rc
     )
 elseif(OS_MACOSX)
     set(NEBULA_PLATFORM_SOURCES
@@ -156,6 +157,9 @@ function(add_nebula_app_target nebula_target entry_source)
 
     if(OS_WINDOWS)
         target_link_libraries(${nebula_target} PRIVATE dwmapi)
+        target_include_directories(${nebula_target} PRIVATE
+            "${CMAKE_SOURCE_DIR}/resources"
+        )
         target_compile_definitions(${nebula_target} PRIVATE
             NOMINMAX
             WIN32_LEAN_AND_MEAN

resources/nebula.rc

@@ -0,0 +1,3 @@
+#include "resource.h"
+
+IDI_APPICON ICON "..\\assets\\images\\branding\\Nebula-Favicon.ico"

resources/resource.h

@@ -0,0 +1,3 @@
+#pragma once
+
+#define IDI_APPICON 1

src/platform/win/nebula_window_win.cpp

@@ -7,6 +7,7 @@
 #include <algorithm>
 #include <string_view>
 
+#include "resource.h"
 #include "ui/paths.h"
 
 namespace nebula::window {
@@ -426,6 +427,20 @@ void nebula::window::NebulaWindowImpl::RegisterClass(HINSTANCE instance_handle)
     window_class.lpfnWndProc = StaticWndProc;
     window_class.hInstance = instance_handle;
     window_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
+    window_class.hIcon = static_cast<HICON>(LoadImageW(
+        instance_handle,
+        MAKEINTRESOURCEW(IDI_APPICON),
+        IMAGE_ICON,
+        GetSystemMetrics(SM_CXICON),
+        GetSystemMetrics(SM_CYICON),
+        LR_DEFAULTCOLOR));
+    window_class.hIconSm = static_cast<HICON>(LoadImageW(
+        instance_handle,
+        MAKEINTRESOURCEW(IDI_APPICON),
+        IMAGE_ICON,
+        GetSystemMetrics(SM_CXSMICON),
+        GetSystemMetrics(SM_CYSMICON),
+        LR_DEFAULTCOLOR));
     window_class.lpszClassName = WindowClassName();
 
     RegisterClassExW(&window_class);