Keep refreshing while the storyboard audio is being prepared

The page polls only while it believes something is working, and preparing
the reel was not on that list - so the progress froze at whatever the last
manual refresh had seen (5/20) while the job ran happily to completion.

Also: treat a reel job older than 15 minutes as gone, the way cuts already
are, so a worker restart cannot leave the button disabled for ever; and
start playing automatically once preparation finishes, since "Prepare and
play" promised both.

trailer.html

@@ -179,6 +179,16 @@
       return s.writing || s.drawing || s.filming; });
   }
 
+  // Preparing the storyboard audio is work too. Without this the page stops
+  // polling and the progress sits at whatever it last happened to see.
+  function busyReel() {
+    var st = String(PKG.reel_state || "");
+    if (!st || st === "ready" || /^failed/.test(st)) return false;
+    var t = Date.parse(PKG.reel_started || "");
+    if (!t) return true;
+    return (Date.now() - t) < 15 * 60 * 1000;   // older than that is gone
+  }
+
   async function load() {
     var r = await api("run_status", { run_id: runId });
     if (!r.ok) { showMsg("msg", r.error || "Could not load that run."); return; }
@@ -194,7 +204,7 @@
   }
 
   function tick() {
-    var busy = DRAFTS.some(busyDraft) || busyRun() || busyShots();
+    var busy = DRAFTS.some(busyDraft) || busyRun() || busyShots() || busyReel();
     if (busy && !timer) timer = setInterval(refresh, 5000);
     if (!busy && timer) { clearInterval(timer); timer = null; }
   }