Show how fast a recording not in real time goes as a speed

The tempo of a recording not in real time read as how many times
slower than real time it was made. "5.1x real time" for a recording
that took five times as long as its video looked like it ran five
times faster.

- The log line at the end and the notice now give seconds of video per
  second it took, with two decimals: 0.20x for the example above.
- It may go above 1x. Nothing holds a recording not in real time back
  to the wall clock, and a cheap scene on a fast screen makes more
  frames a second than the video has.
- A recording of a single frame took 0 s and has no tempo line now,
  instead of a division by zero.

Tests:
- tsc, eslint, Prettier clean
- Gate on melektaus-atx: green, 311 files, 4821 tests
- No check reads the figure itself. 68j looks for "x real time, and
  has every frame", which still matches.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/editor/PlaySession.ts

@@ -322,7 +322,7 @@ export class PlaySession {
     if (steady && !this.state.paused)
       return (
         `Recording "${steady.name}" not in real time: ${steady.seconds.toFixed(1)} s of video, ` +
-        `${steady.slower.toFixed(1)}x real time · Esc stops`
+        `${steady.speed.toFixed(2)}x real time · Esc stops`
       );
     if (this.state.paused) {
       const why = this.breakAt === null ? 'Paused' : `Break in ${this.breakAt}`;

src/viewport/GameRecorder.ts

@@ -115,14 +115,14 @@ export class GameRecorder implements RecordingSink {
   }
 
   /**
-   * How far a recording not in real time has got (#423): seconds of video, and how many times
-   * longer it took; null while none records.
+   * How far a recording not in real time has got (#423): seconds of video, and its speed, seconds
+   * of video per second it took (0.2 is five times slower than real time); null while none records.
    */
-  steadyPace(): { name: string; seconds: number; slower: number } | null {
+  steadyPace(): { name: string; seconds: number; speed: number } | null {
     const info = this.take?.info();
     if (!info || info.realTime || info.state !== 'recording') return null;
     const seconds = info.durationMs / 1000;
-    return { name: info.name, seconds, slower: seconds > 0 ? info.tookMs / info.durationMs : 0 };
+    return { name: info.name, seconds, speed: info.tookMs > 0 ? info.durationMs / info.tookMs : 0 };
   }
 
   stop(): string {

src/viewport/RecordingTake.ts

@@ -588,14 +588,14 @@ export class Take {
     this.tellPace();
   }
 
-  /** How much slower than real time a recording not in real time was made (#423). */
+  /** How fast a recording not in real time was made (#423): seconds of video per second it took. */
   private tellPace(): void {
     const pace = this.steady;
-    if (!pace || pace.seconds <= 0) return;
     const took = this.tookMs / 1000;
+    if (!pace || pace.seconds <= 0 || took <= 0) return;
     this.host.log(
       `Recording "${this.name}" took ${took.toFixed(1)} s for ${pace.seconds.toFixed(1)} s of video, ` +
-        `${(took / pace.seconds).toFixed(1)}x real time, and has every frame`,
+        `${(pace.seconds / took).toFixed(2)}x real time, and has every frame`,
       'info',
     );
   }