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>

config.js

@@ -51,6 +51,35 @@ export const TUNE = {
                        // purpose (that is the point of it), but hordeGrow means a late wave now tries
                        // for ~120 spawns where the old fixed 12 s x 2.5/s could only ever ask for 30,
                        // and a 40-body court on a 270px-wide portrait screen is mush, not menace.
+  // ---- PLAYER HEALTH. A SECOND, SEPARATE damage channel: only ranged attacks touch it. A shambler
+  // reaching you is still instant permadeath (G.mode='eaten') — that decision is settled, see HANDOFF.
+  // There is no HP bar and there never will be: the state shows as blood on the man.
+  playerHp: 4,      // hits from ranged attacks you can absorb before you go down
+  hurtGrace: 1.1,   // s of invulnerability after a hit — a burst must not delete you in one volley
+  healPerDuel: 2,   // hp back for winning a sudden-death duel. THE reason to want the duel.
+  // ---- the rogue ball machine ('m'): real tennis furniture that shoots at you. It never shambles,
+  // so it never crosses your baseline and never scores — it is a standing threat you choose when to
+  // deal with, which is the target-priority decision the game was missing.
+  machEvery: 4,     // games before the first machine can appear, and games between them after
+  machMax: 2,       // machines allowed on court at once
+  machHp: 3,        // splat-quality hits to wreck one
+  machCycle: 3.4,   // s between its shots
+  machWind: 0.9,    // s of TELEGRAPH before each shot — the fairness contract, same idea as shriek()
+  machSpeed: 13,    // m/s it fires at
+  machDmg: 1,       // player hp a shot costs if you don't return it
+  parryPow: 0.85,   // shot quality of a RETURNED machine ball — a parry is a real weapon
+  // ---- chapter bosses: one every bossEvery games, escalating. The racket zombie is demoted to an
+  // occasional opponent (racketEvery) so the boss is the only thing that reads as a wall.
+  bossEvery: 10,    // games between chapter bosses
+  bossHp: 10,       // hp of the FIRST one; each later chapter adds bossHpPerChapter
+  bossHpPerChapter: 8,
+  bossScale: 1.5,   // body height multiplier at chapter 1 (a shambler is 1.8 m)
+  bossScalePer: 0.18, // ...growing per chapter, so chapter 4 towers
+  bossSpeed: 0.42,  // m/s it advances — slow, deliberate, unstoppable
+  bossCycle: 2.6,   // s between its ranged attacks (it uses the machine's projectile)
+  bossVolley: 3,    // shots per attack, fanned
+  racketEvery: 3,   // games between racket-zombie (plain opponent) spawns — was EVERY won game, which
+                    // is why he read as "the boss" and why a real boss would not have stood out
   racketHpPerGame: 0.12, // the racket zombie stiffens as the run goes on (floored into whole hp)
   // ---- damage. Bodies with hp (racket boss 'r', brute 'g') take damage in these units, so a big
   // boss is just a bigger hp number and every weapon stays proportional. Fractions are legal: they