fix(admin): ferme le serveur socket.io en fin de suite de test monitoring

Le hook `after` de admin-monitoring-socket.test.ts appelait seulement
`broadcast.stop()` (qui ne fait que couper l'intervalle de sonde) et
`prisma.$disconnect()`, mais ne fermait jamais le serveur socket.io ni le
`http.Server` en écoute sur le port 0. socket.io garde alors vivants les
timers ping d'engine.io et la socket d'écoute ; comme Mocha tourne sans
`--exit` (.mocharc.json), ce seul handle en fuite empêche le process de se
terminer une fois le dernier test passé.

C'est ce qui bloquait le job `test` en CI : « N passing » affiché, puis
plusieurs heures d'attente jusqu'au kill du runner (runs #80/#81).

Hisse `io` au scope de la suite et le ferme dans `after` via `io.close()`
— ce qui déconnecte les sockets restantes, stoppe les timers d'engine.io
et ferme le `http.Server` attaché.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/api/test/admin-monitoring-socket.test.ts

@@ -51,6 +51,15 @@ function waitForEvent<T>(socket: ClientSocket, event: string, timeoutMs = 1500):
 describe("Admin monitoring — WebSocket push", () => {
   let baseUrl: string;
   let broadcast: MonitoringBroadcastService;
+  // Hoisted to suite scope (not a local in `before`) so `after` can shut
+  // it down. `broadcast.stop()` alone only clears the probe interval — the
+  // socket.io server keeps engine.io's ping timers and the listening
+  // http.Server (port 0) alive, and Mocha runs without `--exit`
+  // (`.mocharc.json`), so that one leaked handle stops the whole process
+  // from ever draining once the last test passes. That is exactly what
+  // stalled CI: the `test` job printed "N passing" and then hung for
+  // hours until the runner was killed.
+  let io: SocketIoServer;
   const clientSockets: ClientSocket[] = [];
 
   // A real listening server, not just createApp()'s bare Express instance
@@ -60,7 +69,7 @@ describe("Admin monitoring — WebSocket push", () => {
   // free one, so this suite never collides with anything else listening.
   before(async () => {
     const httpServer = createServer().httpServer;
-    const io = new SocketIoServer(httpServer, { cors: { origin: "*" } });
+    io = new SocketIoServer(httpServer, { cors: { origin: "*" } });
     broadcast = new MonitoringBroadcastService(io);
     await new Promise<void>((resolve) => httpServer.listen(0, resolve));
     const { port } = httpServer.address() as AddressInfo;
@@ -70,6 +79,12 @@ describe("Admin monitoring — WebSocket push", () => {
 
   after(async () => {
     broadcast.stop();
+    // Disconnects any socket still open, stops engine.io's timers, and
+    // closes the http.Server socket.io was attached to — without this the
+    // suite never lets Node's event loop drain (see the `io` field's note).
+    await new Promise<void>((resolve, reject) => {
+      io.close((err) => (err ? reject(err) : resolve()));
+    });
     await prisma.$disconnect();
   });