Loading pulses actually pulse now

Several "something is happening" indicators were quietly frozen: the skeleton placeholders while a chat message loads, the pulse on a delegated call and on a running sub-thread, and the three blinking dots while a layout area loads. Their animations referred to keyframes written with a Razor escape (@@keyframes) inside plain CSS files, where that escape is not processed — so the keyframes never parsed and the elements just sat still.

The keyframes are plain CSS again, and every one of those indicators moves — so a loading page looks like a loading page instead of a stuck one.