feat: add WebSocket client for export progress

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/src/lib/ws.ts

@@ -0,0 +1,38 @@
+import { getServer } from "./api";
+import { exportStatus, exportCompleted } from "./stores";
+
+let socket: WebSocket | null = null;
+
+export function connectExportWs() {
+  const wsUrl = getServer().replace(/^http/, "ws") + "/ws/export";
+  socket = new WebSocket(wsUrl);
+
+  socket.onmessage = (event) => {
+    const msg = JSON.parse(event.data);
+    switch (msg.type) {
+      case "clip_done":
+        exportCompleted.update(n => n + 1);
+        break;
+      case "all_done":
+        exportStatus.set("done");
+        break;
+      case "error":
+        exportStatus.set("error");
+        console.error("Export error:", msg.msg);
+        break;
+    }
+  };
+
+  socket.onclose = () => {
+    // Reconnect after 2s
+    setTimeout(connectExportWs, 2000);
+  };
+}
+
+export function disconnectExportWs() {
+  if (socket) {
+    socket.onclose = null; // prevent reconnect
+    socket.close();
+    socket = null;
+  }
+}