refactor(build): place the views in the page instead of expanding templates

index.html now lists each view's host and the loading screen itself, so
the gev:template expansion plugin, its view list, the loading-screen
template and the ./build/html export are gone. createApplication takes
omitViews for views an application leaves out; their hosts are removed,
and a view an earlier call rendered is unmounted.

scripts/format-scope.json

@@ -650,7 +650,6 @@
   "src/voice/realtimeBackend.test.mjs",
   "src/agent/worldPacket.test.mjs",
   "src/voice/layerSummary.js",
-  "build/application-html.js",
   "src/app/sources.js",
   "src/ui/composition.js",
   "src/services/application.js",