Remove the HA Dashboard tab and the Qt WebEngine dependency (D40)

DSH-1 ended with a negative result: the Frame's system WebEngine can't be
loaded, and bundling our own failed (no sandbox, ICU resources, Vulkan
abort, empty page). Reverts the tab (60deb43), the container packages
(0676998) and the bundler's WebEngine support (b823ff3, e2cfa8e), and
updates the docs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cmake/BundleQt.cmake

@@ -30,14 +30,6 @@ set(VRDASH_BUNDLE_PLUGINS
     wayland-shell-integration/*.so wayland-graphics-integration-client/*.so
     wayland-decoration-client/*.so xcbglintegrations/*.so)
 
-# Qt WebEngine (bundled only if a dashboard needs it): its helper process, resources and
-# locales. Cross builds point VRDASH_WEBENGINE_PROCESS at the target's QtWebEngineProcess
-# (Debian can't install the arm64 one next to the host's; see docker/cross-arm64.Dockerfile).
-set(VRDASH_WEBENGINE_PROCESS "" CACHE FILEPATH
-    "QtWebEngineProcess to bundle (default: the one of the Qt used for the build)")
-# Locales shipped with WebEngine (the full set is about 35 MB).
-set(VRDASH_WEBENGINE_LOCALES en-US de)
-
 function(vrdash_bundle_qt)
     get_property(targets GLOBAL PROPERTY VRDASH_DASHBOARD_TARGETS)
     get_property(qml_dirs GLOBAL PROPERTY VRDASH_DASHBOARD_QML_DIRS)
@@ -60,14 +52,6 @@ function(vrdash_bundle_qt)
         set(qt_libdir ${qt_prefix}/lib/${CMAKE_LIBRARY_ARCHITECTURE}) # Debian multiarch
     endif()
 
-    # Used by the install script only if a bundled library is Qt WebEngine.
-    set(webengine_process ${VRDASH_WEBENGINE_PROCESS})
-    if(NOT webengine_process)
-        set(webengine_process ${QT6_INSTALL_PREFIX}/${QT6_INSTALL_LIBEXECS}/QtWebEngineProcess)
-    endif()
-    set(webengine_resources ${QT6_INSTALL_PREFIX}/${QT6_INSTALL_DATA}/resources)
-    set(webengine_locales ${QT6_INSTALL_PREFIX}/${QT6_INSTALL_TRANSLATIONS}/qtwebengine_locales)
-
     # The regexes end up inside a quoted string in the generated script: escape backslashes.
     string(REPLACE "\\" "\\\\" bundle_exclude "${VRDASH_BUNDLE_EXCLUDE}")