The notifications schema is already set up for reddit-style
chronological notifications. We simply have to remove the logic that
builds the context and patch up a few places in the frontend that
were expecting full reply trees.
`Comment.header_msg` previously expected the user's own comment to
be top-level in comment replies. Logic is revised to expect the actual
reply.
`files.routes.front.notifications_main` now has reduced query volume
because we aren't expiring the session when marking notifications read.
This also allows us to remove the unused `comms` variable, which is a
makeshift "pattern" of storing duplicate database replies across a
commit so the templates don't requery (thus losing data attached to
the runtime object, like `c.unread` / `c.notif_utc`).
We move the `is_notification_page` flag to the route callers rather
than templates checking `request.path`.
Minor UI style: "Clear all notifications" -> "Mark All Read", since
this was a persistent point of user confusion upstream, with people
expecting their inbox to empty out. Also less margin between notifs
to be consistent with tighter comment display elsewhere and removed
need to separate groups of comments vs single comments.
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