Add chapter bosses and a second damage channel; demote the racket zombie

Steps 4 and 5 of the late-game depth plan.

The ranged channel. A rogue ball machine gets wheeled onto the far court every
four games: it never walks, never crosses your baseline and never scores, so
it is a standing threat you choose when to deal with — the target-priority
decision the game was missing. Its shot is a real arc solved like a serve, not
a flat bolt, so it reads coming in and the swing window has something to meet.
Three outcomes: a swing inside the volley window returns it as your own ball
flying up-court (an extras clone, so "a parry is a weapon" cost nothing to
build), the panic swish bats it away, and letting it reach you costs blood.
The swish path is load-bearing, not politeness: in pretoss the player is
rooted and cannot swing at all.

Contact still kills outright — that stays a separate channel, and killPlayer()
is now the single death path for both causes so the run summary and the best-run
write cannot drift. Health is drawn on the man: procedural spatter at fixed
anchors, a live trickle, and a red wash from the screen edges. No bar. Healing
is winning a duel, which finally gives the duel a reason to be wanted.

Chapter bosses every ten games, with their own sheet — a colossal zombie
groundskeeper hauling a ball hopper, coming apart through arm-off, ribs-out and
headless-still-throwing. Chapter 1 is 10 hp and 2.7 m, chapter 4 is 34 hp and
3.67 m. It outranks the set and duel beats at a clear, because a boss walking
into a standing wave is unreadable. And it fixes the economy: a chapter-4 boss
costs 12 bombs or 100 rounds or 34 side balls against a per-type cap of 9, so
no single weapon can take one and a banked mixed arsenal is mandatory.

The racket zombie is demoted to an occasional opponent, as asked — appearing
every won game is exactly why he read as the boss.

Five silent bugs found on the way, all in HANDOFF: a blast deleted a 34 hp boss
outright (isBoss() exists to stop that class recurring), the machine's hp did
nothing because it fell through to the one-shot fallback, the boss both scored
and fired its card, the machine gated the hand-clear, and a boss died with a
shambler-sized gore burst.

Tennis untouched: 30 tapped points still 50 hits / 0 whiffs. 45-game soak clean
with all four chapters firing.

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

state.js

@@ -49,6 +49,15 @@ export const G = {
   idleHintT: 0,       // s the player has sat in pretoss without touching anything — after a beat the
                       // pull gesture demonstrates itself (render.drawPullHint)
   meleeT: 0,          // s of racket-swish cooldown left
+  // ---- the SECOND damage channel. Only ranged attacks (ball machine, chapter boss) touch this;
+  // a shambler reaching you is still instant permadeath, deliberately. No HP bar anywhere — the
+  // state is drawn as blood on the man (drawChar's spatter + bleedPlayer's live trickle).
+  hp: TUNE.playerHp,
+  hpMax: TUNE.playerHp,
+  hurtT: 0,           // s of post-hit grace left; also drives the red hit flash
+  hurtFlash: 0,       // s of the impact wash left
+  bossDue: 0,         // chapter number the schedule owes you — fired at the next hand-cleared court
+  bossFight: 0,       // chapter number of the boss currently on court, 0 = none. Blocks all other spawns.
   interlude: false,   // sudden-death duel vs the racket zombie: falsy, or {introT} while announcing
   duelLerp: 0,        // 0..1 — how far the court has returned to tennis colors for the duel
   horde: null,        // active horde wave {t, spawnT, mgT} — machine-gun racket, no serving