fix(armor): correct decay_per_hit to decay_per_hp field name

Fixed AttributeError where code was referencing non-existent 'decay_per_hit'
instead of the correct 'decay_per_hp' field on ArmorPiece and ArmorPlate.

- ui/loadout_manager.py: _get_current_config() plate/piece copy
- core/armor_system.py: equip_armor_selection() piece copy

core/armor_system.py

@@ -1362,7 +1362,7 @@ def create_mixed_armor(selections: Dict[ArmorSlot, str]) -> EquippedArmor:
                 item_id=original.item_id,
                 slot=original.slot,
                 set_name=original.set_name,
-                decay_per_hit=original.decay_per_hit,
+                decay_per_hp=original.decay_per_hp,
                 protection=ProtectionProfile(
                     stab=original.protection.stab,
                     cut=original.protection.cut,

ui/loadout_manager.py

@@ -1846,7 +1846,7 @@ class LoadoutManagerDialog(QDialog):
                     item_id=piece.item_id,
                     slot=piece.slot,
                     set_name=piece.set_name,
-                    decay_per_hit=piece.decay_per_hit,
+                    decay_per_hp=piece.decay_per_hp,
                     protection=ProtectionProfile(
                         stab=piece.protection.stab,
                         cut=piece.protection.cut,
@@ -1868,7 +1868,7 @@ class LoadoutManagerDialog(QDialog):
                     plate_copy = ArmorPlate(
                         name=plate.name,
                         item_id=plate.item_id,
-                        decay_per_hit=plate.decay_per_hit,
+                        decay_per_hp=plate.decay_per_hp,
                         protection=ProtectionProfile(
                             stab=plate.protection.stab,
                             cut=plate.protection.cut,