Stadium pass: real crowd, sponsor boards, umpire visible in portrait

- Umpire chair moved courtside (UMP_X 5.6, was 7.1 — which projected to
  x=272 on a 270px-wide portrait canvas: literally one pixel off-screen).
  Tap-cheat coords follow the constant.
- Generated pixel-art night crowd (x_crowd.png) replaces the tier stripes +
  random dots; drawn in 16 columns that bounce independently while the crowd
  cheers. Old procedural crowd kept as the loading fallback.
- Generated courtside sponsor boards (x_ads.png): ACEADE, TOPSPIN & CO,
  VOLLEX, NETTO GRIP, SLAMWICH — tiled at native aspect so lettering is
  never half-cut at any viewport width. Replaces the 'SPLATTER OPEN' text.
- One rot tint over crowd + boards driven by the shared paletteT() (new
  helper), so the stadium dims into splatter and brightens back for duels.

Verified: fresh origin; tennis + splatter screenshots (boards tile cleanly,
crowd reads, tint dims, umpire on-screen beside the court); umpire triple-tap
works at the new chair position; tennis serve benchmark 33/36 across two runs
(first 12 was flub noise); no console errors.

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

config.js

@@ -58,6 +58,7 @@ COURT.svcNear = COURT.netZ + 6.4;  // near service line
 export const PLAYER_H = 1.88;
 export const BOY_H = 1.2;
 export const UMP_H = 3.0;
+export const UMP_X = 5.6; // chair right beside the doubles line — x 7.1 projected off-screen in portrait
 
 // contact rules: outside this height band the ball can't be hit (below = it's past you)
 export const CONTACT = { minY: 0.24, maxY: 2.3 };