fix(auto-thumbnail): [PKG-AUTO-THUMB-07] release terminal canvas storage

docs/compiled/artplayer-plugin-auto-thumbnail.mjs

@@ -301,10 +301,20 @@ function extract(job, config) {
     video.style.width = `${videoWidth}px`;
     video.style.height = `${videoHeight}px`;
     const canvas = document.createElement("canvas");
+    job.own(() => {
+      canvas.height = 0;
+    });
+    job.own(() => {
+      canvas.width = 0;
+    });
     if (!job.active())
       return;
     canvas.width = canvasWidth;
+    if (!job.active())
+      return;
     canvas.height = canvasHeight;
+    if (!job.active())
+      return;
     const ctx = canvas.getContext("2d");
     if (!ctx)
       throw new Error("Auto-thumbnail canvas context is unavailable");