Auto-attack: next target, melee/ranged rule after arts; chain range = cast range

- autoattack: when the target dies, the nearest enemy within close range
  (contact distance + a step) takes over; after an art the hero auto-attacks
  if the art was melee (walked up / cast close by), or ranged with a ranged
  weapon, or ranged with an enemy already in melee range; measured action
  codes and weapon classes in game/engine/orders.h
- chainlightning: jumps reach Blitzschlag's cast range (20 ray segments of
  30, the art code's hit check) via the shared NearestHostile search
- guards: burning bone render hook had the wrong signature (device plus a
  4x4 matrix by value, ret 0x44) and corrupted the stack when fire arrows hit
- crash reports follow the ebp chain before the raw stack scan

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/chain-lightning.md

@@ -55,3 +55,15 @@ ends (a lone enemy is hit once). Two enemies: it bounces between them.
 
 First version (bolts copied for every jump, not using the game's chain)
 replaced the same day: it doubled the jumps.
+
+## Jump range = cast range (2026-10-16)
+
+User request: a jump reaches as far as a cast. Blitzschlag's hit check is in
+the art code (cCreature art switch `0x5222c0`, case 0x21): the ray from the
+caster towards the target is laid out in segments of 30, at most 20, each on
+passable ground (`0x636b60`); the bolt is created on the target only if the
+ray reaches it, otherwise the visible ray just stops. So the cast range is
+20 × 30 = 600. `CastRange()` in `chainlightning.cpp` returns it for every jump
+(also the first hop of extra chains), instead of the game's jump search radius
+(squared 100000, about 316). It is the one place to make the range dynamic
+later. Jumps do not check the ground in between.