Recover a shot left stuck on "filming" by a worker restart

Third occurrence of this shape after cuts and the storyboard reel: a flag
meaning "work is happening" set before an in-memory thread starts, never
cleared when a deploy kills it, and a page that then hides the buttons for
ever. Anything older than 25 minutes is treated as gone.

trailer.html

@@ -181,9 +181,18 @@
   function busyRun() {
     return RUN && /^(writing|reviewing|revising)$/.test(String(RUN.stage || ""));
   }
+  // Work happens in the worker's memory and does not survive a deploy, so a
+  // flag saying "in progress" is only believed while it is recent.
+  function stillFilming(s) {
+    if (!s.filming) return false;
+    var t = Date.parse(s.filming_since || "");
+    if (!t) return false;              // no stamp: from before this existed
+    return (Date.now() - t) < 25 * 60 * 1000;
+  }
+
   function busyShots() {
     return (PKG.shots || []).some(function (s) {
-      return s.writing || s.drawing || s.filming; });
+      return s.writing || s.drawing || stillFilming(s); });
   }
 
   // Preparing the storyboard audio is work too. Without this the page stops
@@ -859,7 +868,7 @@
 
     var tools;
     if (s.drawing) tools = '<span class="busy">drawing…</span>';
-    else if (s.filming) tools = '<span class="busy">filming…</span>';
+    else if (stillFilming(s)) tools = '<span class="busy">filming…</span>';
     else if (EDITING === s.id) {
       tools = '<div style="width:100%"><textarea class="rough" id="rough" rows="3" placeholder="'
         + 'What should change in this shot?">' + esc(s.rough || "") + '</textarea>'