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/BoothScreen.tsx

@@ -408,7 +408,7 @@ export function BoothScreen() {
             <div className="text-term-muted">{occQuery.isError ? t("booth.occUnavailable") : t("common.loading")}</div>
           )}
         </Panel>
-        <div className="min-h-0 flex-1">
+        <div className="flex min-h-0 flex-1 flex-col">
           <ActiveSessions onPick={setActiveTicket} />
         </div>
       </div>