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>

state.js

@@ -30,6 +30,11 @@ export const G = {
   wasServe: false,    // the ball in flight is a serve (first bounce must hit the box)
   splatT: 0,          // time survived in splatter mode — drives the difficulty ramp
   eatenT: 0,          // time since you were eaten — gates the restart tap
+  missLog: [],        // swing diagnostics ring buffer (tennis mode) — inspect via T.G.missLog
+  swingSnaps: null,   // ball-approach samples during the live swing, feeds the miss log
+  rallyNear: null,    // closest the incoming ball got this rally (for never-swung passes)
+  swung: false,       // player swung at least once this rally — whiff log supersedes PASSED
+  lastMiss: null,     // {text, at} — most recent miss reason, drawn on the HUD briefly
 };
 
 export const other = s => s === 'P' ? 'O' : 'P';
@@ -37,6 +42,7 @@ export const deuceSide = () => (score.pts[0] + score.pts[1]) % 2 === 0; // even
 
 export function setupPoint() {
   G.phase = 'pretoss'; ball.active = false; ball.bounces = 0; ball.firstLand = null;
+  G.swingSnaps = null; G.rallyNear = null; G.swung = false;
   if (G.mode === 'splatter') { // always your serve, from wherever you're standing
     score.server = 'P';
     P.pose = 'idle'; P.swingT = -1; P.facing = 1;