Add video resolution and duration options to video generation forms; implement video status polling in frontend

Co-authored-by: Copilot <copilot@github.com>

frontend/app/static/app.js

@@ -37,4 +37,48 @@ document.addEventListener("DOMContentLoaded", () => {
       if (panel) panel.classList.add("active");
     });
   });
+
+  // ── Video status polling ───────────────────────────────
+  const pollDiv = document.getElementById("video-poll-status");
+  if (pollDiv) {
+    const pollingUrl = pollDiv.dataset.pollingUrl;
+    const statusText = document.getElementById("poll-status-text");
+    const videoContainer = document.getElementById("poll-video-container");
+
+    const interval = setInterval(async () => {
+      try {
+        const resp = await fetch(
+          "/generate/video/status?polling_url=" +
+            encodeURIComponent(pollingUrl),
+        );
+        if (!resp.ok) return;
+        const data = await resp.json();
+
+        if (statusText) {
+          statusText.innerHTML = "Status: <strong>" + data.status + "</strong>";
+        }
+
+        if (data.status === "completed") {
+          clearInterval(interval);
+          if (data.video_url && videoContainer) {
+            const vid = document.createElement("video");
+            vid.src = data.video_url;
+            vid.controls = true;
+            vid.className = "generated-video";
+            videoContainer.appendChild(vid);
+            const msg = pollDiv.querySelector("p");
+            if (msg) msg.textContent = "Video ready!";
+          }
+        } else if (data.status === "failed") {
+          clearInterval(interval);
+          pollDiv.innerHTML =
+            '<div class="alert alert-error">Generation failed: ' +
+            (data.error || "Unknown error") +
+            "</div>";
+        }
+      } catch (e) {
+        console.error("Video polling error:", e);
+      }
+    }, 5000);
+  }
 });