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>

src/game/engine/orders.h

@@ -67,9 +67,20 @@ void OnCreatureOrder(CreatureOrderFn callback);
 constexpr size_t kCreatureId = 0xc;
 constexpr size_t kCreatureX = 0x1c;
 constexpr size_t kCreatureY = 0x20;
-// +0x150: low word the current action (0 none, 1 art, 3 attack, 8 ...), high
-// word its phase; 0x10000 when standing idle.
+// +0x150: low word the current action, high word its phase; 0x10000 when
+// standing idle. Measured on the hero: 1 walking (also up to a target),
+// 3 weapon attack, 4 casting a spell (2026-10-16), 6 dying, 8 an art seen
+// after walking up (2026-10-15, presumably a combat move).
 constexpr size_t kCreatureAction = 0x150;
+enum CreatureAction : int32_t {
+    kActionIdle = 0,
+    kActionWalk = 1,
+    kActionAttack = 3,
+    kActionCastSpell = 4,
+    kActionDying = 6,
+    kActionCombatMove = 8,
+};
+inline int32_t CurrentAction(const void* creature);
 
 // cCreature::IsAlive (0x548ef0): not dying (+0x150 == 6), not dead (+0xfc ==
 // 9), health (+0x4d8) left.
@@ -96,4 +107,37 @@ inline int32_t CreatureField(const void* creature, size_t offset) {
     return *reinterpret_cast<const int32_t*>(static_cast<const uint8_t*>(creature) + offset);
 }
 
+inline int32_t CurrentAction(const void* creature) {
+    return CreatureField(creature, kCreatureAction) & 0xffff;
+}
+
+// The distance at which two creatures touch (0x4dbaa0 on one, (the other)):
+// the mean of their body radii by object type (heroes 110 with a weapon, 80
+// without; monsters 70..480). A melee attacker swings from about there
+// (measured: heroes started swings at 117..149).
+inline int ContactDistance(void* creature, void* other) {
+    using Fn = int(__fastcall*)(void*, void*, void*);
+    return reinterpret_cast<Fn>(0x004dbaa0)(creature, nullptr, other);
+}
+
+// The creature's weapon class (0x546df0, (0)): from the weapons in its hands
+// (+0x1d4 / +0x1d8, item type +0x1e), in the order of the motion sets:
+// 0 bare hands, 1 one-handed, 2 two-handed, 3 two-handed axe, 4 staff,
+// 5 dagger, 6 throwing, 7 bow, 8 two weapons, 9 / 10 blades, 11 whip,
+// 12 crossbow, 13 pistol.
+inline int WeaponClass(void* creature) {
+    using Fn = short(__fastcall*)(void*, void*, int);
+    return reinterpret_cast<Fn>(0x00546df0)(creature, nullptr, 0);
+}
+inline bool HasRangedWeapon(void* creature) {
+    const int c = WeaponClass(creature);
+    return c == 6 || c == 7 || c == 12 || c == 13;
+}
+
+// The nearest living creature hostile to `attacker` within `maxDistance` of
+// `from` (a creature), other than `except` and other player heroes; one not
+// in `avoid` if there is any. 0 if none.
+uint32_t NearestHostile(void* attacker, void* from, double maxDistance, uint32_t except = 0,
+                        const uint32_t* avoid = nullptr, size_t avoidCount = 0);
+
 } // namespace game