feat: complete QML shell migration and ship 0.0.8 Arch package

Replace the Widgets main shell with AppShellHost + QML routes, add a QML
independent player window, and remove the legacy player/page Widgets stack.
Also wire settings cache/proxy actions, fix quit-time engine teardown, improve
list/home scroll performance, and update Arch packaging to 0.0.8.

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.19)
 
-project(qEmby VERSION 0.0.6 LANGUAGES CXX)
+project(qEmby VERSION 0.0.8 LANGUAGES CXX)
 
 if(APPLE)
     set(CMAKE_OSX_DEPLOYMENT_TARGET 13.0)
@@ -184,6 +184,11 @@ unset(_qemby_saved_skip_install_rules)
 set(QWINDOWKIT_INSTALL OFF CACHE BOOL
     "Disable QWindowKit development install rules inside qEmby" FORCE)
 
+# QML 外壳迁移需要 QWK::QuickWindowAgent 为 ApplicationWindow 提供无边框窗口；
+# 上游默认只构建 widgets 模块。
+set(QWINDOWKIT_BUILD_QUICK ON CACHE BOOL
+    "Build QWindowKit quick module for the QML shell" FORCE)
+
 add_subdirectory(libs/qwindowkit)
 add_subdirectory(libs/qwindowkit/examples/shared)
 add_subdirectory(src/qEmbyCore)