feat: add frontend test infrastructure and fix CI workflow

- Fix pnpm version mismatch in test_next_server.yml (8 → auto-detect 10)
- Add concurrency group to cancel stale CI runs
- Remove redundant setup-node step
- Update jest.config.js for jsdom + tsx support
- Add meetingStatusBatcher integration test (3 tests)
- Extract createMeetingStatusBatcher factory for testability

www/app/lib/meetingStatusBatcher.ts

@@ -8,18 +8,24 @@ type MeetingStatusResult = {
   upcoming_events: components["schemas"]["CalendarEventResponse"][];
 };
 
-export const meetingStatusBatcher = create({
-  fetcher: async (roomNames: string[]): Promise<MeetingStatusResult[]> => {
-    const unique = [...new Set(roomNames)];
-    const { data } = await client.POST("/v1/rooms/meetings/bulk-status", {
-      body: { room_names: unique },
-    });
-    return roomNames.map((name) => ({
-      roomName: name,
-      active_meetings: data?.[name]?.active_meetings ?? [],
-      upcoming_events: data?.[name]?.upcoming_events ?? [],
-    }));
-  },
-  resolver: keyResolver("roomName"),
-  scheduler: windowScheduler(10),
-});
+const BATCH_WINDOW_MS = 10;
+
+export function createMeetingStatusBatcher(windowMs: number = BATCH_WINDOW_MS) {
+  return create({
+    fetcher: async (roomNames: string[]): Promise<MeetingStatusResult[]> => {
+      const unique = [...new Set(roomNames)];
+      const { data } = await client.POST("/v1/rooms/meetings/bulk-status", {
+        body: { room_names: unique },
+      });
+      return roomNames.map((name) => ({
+        roomName: name,
+        active_meetings: data?.[name]?.active_meetings ?? [],
+        upcoming_events: data?.[name]?.upcoming_events ?? [],
+      }));
+    },
+    resolver: keyResolver("roomName"),
+    scheduler: windowScheduler(windowMs),
+  });
+}
+
+export const meetingStatusBatcher = createMeetingStatusBatcher();