fix(booth): make the Active Sessions list scrollable

The session list filled to its content height instead of clipping, so a long list
(29 sessions) overflowed the column instead of scrolling — unlike the live feed.

The ActiveSessions Panel sat in a plain block wrapper, so it sized to content and its
inner `h-full overflow-y-auto` had no bounded height to scroll within. Make the wrapper
a flex column and give the Panel `flex-1` so it fills the column; the inner scroll area
is then bounded and scrolls — matching the live-feed treatment.

Verified live (Playwright): the scroll container is now 437px tall over 1118px of
content → scrollable, while the live feed is unchanged.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/web/src/ActiveSessions.tsx

@@ -71,7 +71,7 @@ export function ActiveSessions({ onPick }: { onPick: (identity: string) => void
           {sessions.length} {t("booth.insideCount")}
         </span>
       }
-      className="min-h-0"
+      className="min-h-0 flex-1"
     >
       <div className="h-full overflow-y-auto pr-1">
         {sessions.length === 0 ? (