implement moderator dashboard

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We've got enough traffic that moderation is becoming an increasingly big concern. Good problems. Our current DMCA moderation flow isn't great... I don't know what everyone does, but I generally:

1. Get an infringing URL from an email, grab the playback ID from that portion of the URL
2. Head over to . Middle-click the stream name to open the stream detail page. Also get the User ID.
3. Paste the User ID into the appropriate place to get to the user detail page. Ban the user.
4. Go to the stream detail page. Kick off the users' stream.
5. Manually send an email informing the user they're banned.

There are a few other workflows but they all usually involve that many steps. Here's what I propose for a more streamlined interface:

1. New admin page. At the top is one big box. That big box can take
a. User ID
b. Playback ID/Stream Key/Stream ID
c. A full CDN playlist/segment URL, from which we will extract the Playback ID
2. Whichever you input, two columns down below:
a. User information
b. Currently-active streams. Ideally we'd have thumbnails there but we could also just embed lowest-rendition video segments?
3. A big "kickban" that bans the user, shuts down the streams, and sends the email.

No files, tests, or entry points are named. Start by mapping the existing admin tools, user and stream detail workflows described in the issue, then define the dashboard's accepted identifiers and kickban behavior; done means one page can find the user or stream, show active streams, and perform the proposed moderation actions.

Written by the indexing model from the issue text.