feat: add typed moderation broadcaster

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/moderation/broadcaster.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it, vi } from "vitest";
+import { createBroadcaster } from "../../src/moderation/broadcaster";
+
+function client() {
+  return { readyState: 1, send: vi.fn() };
+}
+
+describe("createBroadcaster", () => {
+  it("sends JSON events to open clients", () => {
+    const ws = client();
+    const broadcaster = createBroadcaster();
+
+    broadcaster.addClient(ws as any);
+    broadcaster.messageAnalyzed({ id: "m1", ai_status: "clean" } as any);
+
+    expect(ws.send).toHaveBeenCalledTimes(1);
+    expect(JSON.parse(ws.send.mock.calls[0][0])).toMatchObject({
+      type: "message_analyzed",
+      data: { id: "m1", ai_status: "clean" },
+    });
+  });
+
+  it("skips closed clients", () => {
+    const ws = { readyState: 3, send: vi.fn() };
+    const broadcaster = createBroadcaster();
+
+    broadcaster.addClient(ws as any);
+    broadcaster.messageDeleted({ id: "m1", deleted_at: 123 });
+
+    expect(ws.send).not.toHaveBeenCalled();
+  });
+});