Miss log: every tennis swing logs why it failed, last reason shown on HUD

Whiffed swings sample the ball's approach each frame and classify the
miss at swing expiry: tap too early (with ms), tap too late, ball line
wide, too high/low, out of reach. Balls that die on your side without
a swing log as PASSED with closest-approach data. Ring buffer of 50 at
T.G.missLog; the latest miss reason flashes on the HUD for 3.5s
(TUNE.missHud to disable). CPU serve-return benchmark still 11/12.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

render.js

@@ -290,5 +290,9 @@ export function render() {
     ctx.font = 'bold 14px monospace'; ctx.fillStyle = '#ffffff';
     ctx.fillText(G.flash.text, W / 2, 60 + Math.sin(G.flash.t * 20) * 1);
   }
+  if (TUNE.missHud && G.lastMiss && G.idleT - G.lastMiss.at < 3.5) { // last miss reason, live
+    ctx.font = 'bold 8px monospace'; ctx.fillStyle = '#ff9060';
+    ctx.fillText(G.lastMiss.text.toUpperCase(), W / 2, H - 28);
+  }
   ctx.textAlign = 'left';
 }