feat: menu-bar-only app (no Dock icon) + macOS app icon

- NSApplicationActivationPolicyAccessory: app hidden from Dock and
  app switcher; lives only in the menu bar tray
- resources/clouck.icns: programmatic icon (green gradient rounded
  square, white dial, 10:10 hands), all sizes 16-1024 incl @2x
- CMake: MACOSX_BUNDLE_ICON_FILE wired, icns shipped in Resources/

CMakeLists.txt

@@ -47,10 +47,18 @@ elseif(APPLE)
     list(APPEND HEADERS window_helper_macos.h)
 endif()
 
+# macOS app icon
+if(APPLE)
+    set(MACOSX_BUNDLE_ICON_FILE clouck.icns)
+    set(APP_ICON_MACOSX ${CMAKE_CURRENT_SOURCE_DIR}/resources/clouck.icns)
+    set_source_files_properties(${APP_ICON_MACOSX} PROPERTIES MACOSX_PACKAGE_LOCATION "Resources")
+endif()
+
 # Create executable
 qt6_add_executable(Clouck WIN32 MACOSX_BUNDLE
     ${SOURCES}
     ${HEADERS}
+    ${APP_ICON_MACOSX}
 )
 
 # Platform-specific sources and libraries