feat(icons): add Catppuccin Mocha icon override infrastructure

Set up the foundation for custom Kindred Create icons:

- Add kindred-icons/ directory with Catppuccin Mocha themed SVG icons
- Modify BitmapFactory to prioritize kindred-icons/ in search path
- Add CMake install rules to package icons with application
- Include documentation (README.md) with design guidelines
- Add 12 initial icons as proof of concept:
  - File: document-new, document-open, document-save
  - Edit: edit-undo, edit-redo, edit-copy, edit-cut, edit-paste, delete
  - View: zoom-in, zoom-out, view-refresh
  - System: preferences-system

All icons follow the standard template:
- 32x32 viewBox
- Rounded rectangle background (rx=4, surface0 #313244)
- Catppuccin Mocha color palette

Closes #3

src/Gui/BitmapFactory.cpp

@@ -63,6 +63,13 @@ BitmapFactoryInst& BitmapFactoryInst::instance()
     if (!_pcSingleton) {
         _pcSingleton = new BitmapFactoryInst;
         std::map<std::string, std::string>::const_iterator it;
+
+        // Kindred Create custom icons - highest priority
+        // These override default FreeCAD icons with Catppuccin Mocha themed versions
+        _pcSingleton->addPath(
+            QStringLiteral("%1/kindred-icons").arg(QString::fromStdString(App::Application::getHomePath()))
+        );
+
         it = App::GetApplication().Config().find("ProgramIcons");
         if (it != App::GetApplication().Config().end()) {
             QString home = QString::fromStdString(App::Application::getHomePath());

src/Gui/CMakeLists.txt

@@ -1618,3 +1618,15 @@ INSTALL(
     DESTINATION
         ${CMAKE_INSTALL_DATADIR}/3Dconnexion
 )
+
+# Kindred Create custom icons - Catppuccin Mocha themed overrides
+INSTALL(
+    DIRECTORY
+        ${CMAKE_SOURCE_DIR}/kindred-icons/
+    DESTINATION
+        kindred-icons
+    FILES_MATCHING
+        PATTERN "*.svg"
+        PATTERN "*.png"
+        PATTERN "README.md"
+)