Trade the tutorial for a screen that counts the dead

The menus were placeholders next to the art. Three screens now: a title over
an empty, dimmed, blood-stained court; a MATCH SETUP screen where each court
wears meters read straight off its own bounce numbers; and BODY COUNT, which
needed the game to start measuring anything at all.

stats.js keeps one capped array of per-run records — all time, last match and
seven days are three filters over it rather than three counters that can drift
apart. Kills file under the body AND the weapon: killZombie only ever knew an
index, so every damage loop stamps the cause on its way past.

The tutorial is gone. Marvin explained what the in-game modals already teach,
and his stage is where the stats live now.

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

render.js

@@ -198,7 +198,10 @@ function drawRunOff() {
 
 // ---------------------------------------------------------------- sprites ----
 // assets/<name>.png; game falls back to code-drawn figures until sprites load.
-const SPRV = 84; // asset cache-buster — bump with main.js?v=N (see the img.src note below)
+// Asset cache-buster — bump with main.js?v=N (see the img.src note below). EXPORTED because the
+// menu screens hang <img> tags on the same files, and two copies of this number is one copy too
+// many: the one that does not get bumped is the one that serves a cached 404.
+export const SPRV = 85;
 const SPR = {};
 for (const n of ['p_idle1','p_idle2','p_bounce','p_bounce2','p_toss','p_smash','p_run1','p_run2','p_run3','p_run4','p_swing1','p_swing2','p_die1','p_die2','p_die3','p_die4','p_die5',
                  'p_pull', // the serve wind-up: the racket dropping behind him while the pull is drawn