refactor dashboard room activity fetching

Refactor selected-room dashboard activity fetching, split Rooms i18n, and tighten mobile usage layout.

apps/dashboard/src/useRoomActivity.ts

@@ -0,0 +1,68 @@
+import { useCallback, useEffect, useState } from 'react';
+
+import { fetchRoomTimeline, type DashboardRoomActivity } from './api';
+
+export type RoomActivityMap = Record<string, DashboardRoomActivity>;
+
+interface UseSelectedRoomActivityOptions {
+  active: boolean;
+  pollMs?: number;
+  selectedRoomJid: string | null;
+}
+
+export function useSelectedRoomActivity({
+  active,
+  pollMs = 2000,
+  selectedRoomJid,
+}: UseSelectedRoomActivityOptions): {
+  refreshRoom: (roomJid: string) => Promise<DashboardRoomActivity>;
+  roomActivity: RoomActivityMap;
+  roomActivityLoading: boolean;
+} {
+  const [roomActivity, setRoomActivity] = useState<RoomActivityMap>({});
+  const [roomActivityLoading, setRoomActivityLoading] = useState(false);
+
+  const refreshRoom = useCallback(async (roomJid: string) => {
+    const activity = await fetchRoomTimeline(roomJid);
+    setRoomActivity((previous) => ({
+      ...previous,
+      [roomJid]: activity,
+    }));
+    return activity;
+  }, []);
+
+  useEffect(() => {
+    if (!active || !selectedRoomJid) {
+      setRoomActivityLoading(false);
+      return undefined;
+    }
+
+    let cancelled = false;
+    let inFlight = false;
+    let pollIntervalId: number | null = null;
+
+    const fetchOnce = async (initial: boolean) => {
+      if (cancelled || inFlight) return;
+      inFlight = true;
+      if (initial) setRoomActivityLoading(true);
+      try {
+        await refreshRoom(selectedRoomJid);
+      } catch {
+        /* Keep the last good timeline snapshot. */
+      } finally {
+        inFlight = false;
+        if (!cancelled && initial) setRoomActivityLoading(false);
+      }
+    };
+
+    void fetchOnce(true);
+    pollIntervalId = window.setInterval(() => void fetchOnce(false), pollMs);
+
+    return () => {
+      cancelled = true;
+      if (pollIntervalId !== null) window.clearInterval(pollIntervalId);
+    };
+  }, [active, pollMs, refreshRoom, selectedRoomJid]);
+
+  return { refreshRoom, roomActivity, roomActivityLoading };
+}