Polish round: modal system, softened palette, pixel font, and the 14 plan items

The three foundations first, since everything else leans on them:

- G.modal is the only thing that stops the world. update() early-returns on it
  so no zombie steps, no ball flight, no spawn timers run while a popup is on
  screen — you can read it without being eaten. Dismissal swallows the gesture;
  the pointerdown dismisser is registered only on pointer:fine, because on touch
  pointerdown beats touchstart and a shared handler cleared the modal and then
  served with the same thumb.
- UI in config.js is the accent palette. The arcade primaries were shouting over
  the artwork; the gore reds deliberately stay loud.
- Every canvas font string now goes through F(). Bare `monospace` resolved to
  Courier — a slab serif — which was the "generic serif" bug, not taste.

Then: weapons are only ever WON. deliverTin() has exactly one caller now
(resolveInterlude('P')); the old game schedule calls the DUEL instead, fired off
proceedAfterClear() where the court is guaranteed empty. Four popups (splatter
tutorial with a generated illustration, first duel, weapon received, horde),
wCap 9 with the tin amounts tunable, a 5-hp brute that comes apart over four
wound skins, fire that ignites the neighbours and chains outward, a three-stage
death where you become the biggest gore mound on the court, and a 7s changeover
with a ball boy who finally has a mop.

New art: assets/logo.png, x_howto, z_gw2-4, x_boymop1-4, plus assets/_key.py for
standalone art (chroma-key + crop, no frame splitting, no forced sprite height).

Benchmarks re-run and holding: CPU returns 23/24 serves, 30 human-tapped points
= 50 hits / 0 whiffs, 26 simulated games with no exceptions.

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

config.js

@@ -30,7 +30,8 @@ export const TUNE = {
   zSpawnStep: 0.22, // spawn-gap reduction per finished game
   zMax: 3,          // shamblers on court in game 1 (cap grows +1 per game to zMaxCap; 0 = spawns off, for tests)
   zMaxCap: 14,      // absolute shambler cap
-  changeoverT: 4.5, // s the changeover breather lasts (after odd games, as the rules demand)
+  changeoverT: 7.0, // s the changeover breather lasts (after odd games, as the rules demand)
+  boyMopSpeed: 4.0, // m/s a MOPPING ball boy crosses at (a fetching one still sprints at 7.5)
   gameBeatT: 1.6,   // s the game-end beat lasts on even (non-changeover) games
   eatenR: 0.9,      // m a shambler must close to eat you — matches the visual sprite overlap
   zSnap: 0.9,       // m of lateral slack at zero range — the aim cone's base width (fat-thumb forgiveness)
@@ -62,10 +63,15 @@ export const TUNE = {
   backstopPop: 1.8,   // m/s of lift off the fence, so the rebound travels back instead of dying at the net posts
   meleeCool: 1.0,   // s between racket swishes — melee is the panic button, not the default
   zPierce: 0.75,    // pace a ball keeps after a splatter — hot balls plow through lined-up pairs
-  ballChangeFirst: 3, // game of the first new-balls delivery (real rule: 7, then every 9 — too sparse here)
-  ballChangeEvery: 4, // games between deliveries after the first
+  // The schedule calls the DUEL, not the tin: weapons are only ever won, but a duel comes round
+  // on its own so there is always a chance at one. Fires off the next hand-cleared wave.
+  duelFirst: 2,     // game after which the first scheduled sudden-death duel is called
+  duelEvery: 3,     // games between scheduled duels after the first
   bombMax: 3,       // bomb balls in a fresh tin
-  wCap: 3,          // per-type cap on the courtside rack — tins accumulate, but only so many
+  tinTriples: 3,    // triple-serves in a fresh tin
+  tinFlames: 3,     // flame balls in a fresh tin
+  tinGuns: 1,       // machine-gun charges in a fresh tin
+  wCap: 9,          // per-type cap on the courtside rack — tins accumulate, but only so many
   rackH: 22,        // px height of the bottom weapon rack (feel knob: how much court it covers)
   bombRadius: 2.5,  // m blast radius of a bomb ball
   hordeLen: 12,     // s a horde wave lasts
@@ -76,8 +82,14 @@ export const TUNE = {
   runnerSpeed: 3.2, // runner ('f') speed multiplier over the shamble
   runnerVMax: 4.2,  // hard runner speed cap — the late-game ramp must stay humanly reactable
   shamblerHp: 2,    // splat-quality hits a classic shambler ('a'/'b') soaks before it dies — only the runner ('f') is still one-shot glass
+  // fire: the flame ball no longer just kills what it touches, it starts an epidemic.
+  burnTime: 3.0,    // s a body burns before the fire goes out
+  burnDps: 2.0,     // hp lost per second while burning — burnTime*burnDps must exceed bruteHp or tanks walk out of the fire
+  burnSpread: 1.3,  // m — a burning body ignites anything this close, every frame it burns
+  burnIgniteR: 2.6, // m — the flame ball's ignition radius around the body it kills
+  burnPanic: 1.0,   // walk-speed multiplier while burning (1 = off; crank it for panicked sprinting)
   setCardT: 2.0,    // s the centered SET card holds (the 'kurze unterbrechung' before the horde)
-  bruteHp: 2,       // splat-quality hits (or pellets) a brute ('g') soaks before it dies
+  bruteHp: 5,       // splat-quality hits (or pellets) a brute ('g') soaks before it dies — one wound skin per stage
   shieldDown: 1.5,  // s a shield zombie's ('s') chair stays dropped after a block — the kill window
   meleeRange: 1.7,  // m — a racket swish cleaves shamblers this close to you
   racketHp: 3,      // splat-quality hits a racket zombie (mini-boss) takes before it dies
@@ -88,6 +100,17 @@ export const TUNE = {
   killPips: 1,      // splatter: show the kills-to-next-point pips on the scoreboard
 };
 
+// the death animation's timeline, in seconds of G.eatenT. A: thrash · B: you burst into gore
+// · C: the summary fades in. The restart tap is gated past the whole thing so a panic tap
+// during the burst can't skip it.
+export const EATEN_BURST = 0.5, EATEN_SUMMARY = 1.6, EATEN_RESTART = 2.2;
+
+// UI accent colours, one place so the whole HUD can be re-tuned at once. Deliberately
+// desaturated from the original arcade primaries: they were shouting over the artwork.
+// (NOT the gore — blood and piles keep their loud reds; only text and interactive UI.)
+export const UI = { hot: '#d9705f', warm: '#e0cc72', pick: '#cbd06a', cream: '#e8e8dc',
+                    dim: '#8fa0b8', bad: '#a34a42', ball: '#dbe063' };
+
 export const COURT = { L: 23.77, W: 8.23, dblW: 10.97, netZ: 11.885, netH: 0.914, netW: 10.06 };
 COURT.svcFar = COURT.netZ - 6.4;   // far service line
 COURT.svcNear = COURT.netZ + 6.4;  // near service line