Add Nebula.Windows with Sway IPC backend

Introduces a new `core/windows` module (`Nebula.Windows`) with `WindowService`, window/workspace models, and a Sway IPC backend for live window tracking and control (focus, close, move/resize, snap, maximize/restore, minimize, workspace switch). The desktop shell now links this module, uses compositor focus for top-bar active app text, and adds an Open Windows section in the launcher with focus/close actions.

Also updates application metadata handling to parse `StartupWMClass` and map window `app_id`/class to friendly names and icons, and revises Sway config/docs for the new floating-first Desktop 0.2 behavior with temporary compositor-provided decorations.

shells/desktop/shell/CMakeLists.txt

@@ -13,7 +13,7 @@ set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
-find_package(Qt6 6.4 REQUIRED COMPONENTS Core Gui Qml Quick)
+find_package(Qt6 6.4 REQUIRED COMPONENTS Core Gui Qml Quick Network)
 find_package(LayerShellQt REQUIRED)
 
 qt_standard_project_setup(REQUIRES 6.4)
@@ -30,6 +30,11 @@ add_subdirectory(
     "${CMAKE_CURRENT_BINARY_DIR}/nebula-applications"
 )
 
+add_subdirectory(
+    "${CMAKE_CURRENT_SOURCE_DIR}/../../../core/windows"
+    "${CMAKE_CURRENT_BINARY_DIR}/nebula-windows"
+)
+
 qt_add_executable(nebula-shell
     src/main.cpp
     src/DesktopIconProvider.cpp
@@ -48,6 +53,7 @@ set(NEBULA_SHELL_QML_FILES
     qml/components/SystemArea.qml
     qml/components/Launcher.qml
     qml/components/AppItem.qml
+    qml/components/OpenWindowItem.qml
     qml/mock/MockApps.qml
 )
 
@@ -79,6 +85,7 @@ qt_add_qml_module(nebula-shell
         QtQuick
         Nebula.UI
         Nebula.Applications
+        Nebula.Windows
 )
 
 target_link_libraries(nebula-shell
@@ -90,6 +97,7 @@ target_link_libraries(nebula-shell
         LayerShellQt::Interface
         NebulaUI
         NebulaApplications
+        NebulaWindows
 )
 
 if(TARGET NebulaUIplugin)
@@ -98,6 +106,9 @@ endif()
 if(TARGET NebulaApplicationsplugin)
     target_link_libraries(nebula-shell PRIVATE NebulaApplicationsplugin)
 endif()
+if(TARGET NebulaWindowsplugin)
+    target_link_libraries(nebula-shell PRIVATE NebulaWindowsplugin)
+endif()
 
 # Generated nebula-shell_qmltyperegistrations.cpp includes "OutputTracker.hpp"
 # via __has_include. Keep src/ on the include path so that succeeds.