fix(forge): show a filed issue in the list without a refresh

Filing an issue from the repository panel left the list exactly as it was.
The issue existed — the panel opened on it — but the row only turned up
after hitting refresh by hand.

The list had in fact been re-read, and that was the bug. It is served from
GitHub's search index, which lags a write by seconds to minutes, while the
create goes to the core API and has no such lag. Re-reading the moment an
issue is filed therefore answers with a page from before it existed, and
landing that page is what took the new row back off the screen. Every other
write on this panel already refuses to re-read for exactly this reason;
filing was the one still doing it.

The row now comes from what the create itself answered with, like the rest
of them. What the re-read was really buying was placement — a new issue is
not in the pull-request list at all, and under a narrowed filter it may not
be in this one either — so that is decided from the filters the page already
holds. It declines on the other tab, past page one, under an order that
sorts a new issue to the last page, and under any state, assignee, search or
label the row cannot match. When it declines the list is left untouched: the
detail panel opens on the issue regardless, so nothing filed goes unseen.

A list response already in flight when the issue was filed cannot contain it
and would drop it, so a note keyed to the exact view — folder, tab, filters,
order and page — puts it back. Anything coarser puts it back in the wrong
place: keyed to the tab alone, a row filed while nothing was filtered
reappears in a filtered page that had correctly left it out.

The tab badge moves with it, counted off the reconciled page so the digit
and the rows beneath it are the same page. `reachable_count` deliberately
does not move — it is the ceiling on what the forge will page through at
all rather than a tally, and raising it would number a page that answers
422.