client: list quicktime as supported in UI

[a99984b1799]

Really minor issue, but .mov isn't listed as an "allowed extension" in the UI despite it recently seeing support.

I haven't read too much into szuru's architecture, but if possible I feel it would be better to extrapolate this text from a canonical source (it looks like supported MIME types are listed above?) rather than having to manually update it.

Thanks!