fix(mod): fix culture pillar, on_game_start override, event backgrounds

- Add head_determination = head_determination_domain to all three
  Scadrian cultures (required by CK3 1.18)
- Move on_game_start initialization from effect block to
  mistborn_init.0001 event to avoid overriding vanilla's effect block
- Replace non-existent event backgrounds (corridor.dds, battlefield.dds)
  with valid vanilla keys (study, wilderness)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lords_of_ash/common/culture/cultures/00_scadrial_cultures.txt

@@ -1,4 +1,4 @@
-# Mistborn: The Final Empire - Cultures of Scadrial
+# Mistborn: The Final Empire - Cultures of Scadrial
 # Three main cultural groups exist: the ruling nobles, the oppressed skaa, and the Terris people.
 
 noble_scadrian = {
@@ -8,6 +8,7 @@ noble_scadrian = {
 	heritage = heritage_scadrial
 	language = language_scadrial
 	martial_custom = martial_custom_male_only
+	head_determination = head_determination_domain
 
 	name_list = name_list_scadrial_noble # TODO: Create custom name lists
 
@@ -33,6 +34,7 @@ skaa = {
 	heritage = heritage_scadrial
 	language = language_scadrial
 	martial_custom = martial_custom_male_only
+	head_determination = head_determination_domain
 
 	name_list = name_list_scadrial_skaa # TODO: Create custom name lists
 
@@ -57,6 +59,7 @@ terris = {
 	heritage = heritage_scadrial
 	language = language_terris
 	martial_custom = martial_custom_male_only # Terris men are made into eunuch stewards
+	head_determination = head_determination_domain
 
 	name_list = name_list_terris # TODO: Create custom name lists
 

lords_of_ash/common/on_action/mistborn_on_actions.txt

@@ -1,4 +1,4 @@
-############################################
+############################################
 # Mistborn: The Final Empire - On Actions
 # Hooks into CK3's event system for Mistborn mechanics
 ############################################
@@ -131,48 +131,8 @@ on_yearly_pulse = {
 # ON GAME START - Initialize variables for starting rulers
 # ============================================================
 on_game_start = {
-	effect = {
-		every_ruler = {
-			limit = {
-				is_ruler = yes
-				highest_held_title_tier >= tier_county
-			}
-			set_variable = {
-				name = lord_ruler_attention
-				value = 0
-			}
-
-			# Grant starting metal supplies to Allomancers
-			if = {
-				limit = {
-					is_allomancer_trigger = yes
-					is_noble_scadrian_trigger = yes
-				}
-				add_character_modifier = {
-					modifier = metal_reserves_abundant
-					years = 2
-				}
-			}
-			else_if = {
-				limit = {
-					is_allomancer_trigger = yes
-					is_skaa_trigger = yes
-				}
-				add_character_modifier = {
-					modifier = metal_reserves_low
-					years = 1
-				}
-			}
-			else_if = {
-				limit = {
-					is_allomancer_trigger = yes
-				}
-				add_character_modifier = {
-					modifier = metal_reserves_abundant
-					years = 2
-				}
-			}
-		}
+	events = {
+		mistborn_init.0001
 	}
 }
 

lords_of_ash/events/game_start_events.txt

@@ -0,0 +1,58 @@
+############################################
+# Mistborn Mod - Game Start Initialization
+# Namespace: mistborn_init
+############################################
+
+namespace = mistborn_init
+
+# ============================================================
+# 0001 - Initialize starting rulers
+# Fired from on_game_start events list
+# ============================================================
+mistborn_init.0001 = {
+	type = character_event
+	hidden = yes
+
+	trigger = {
+		is_ruler = yes
+		highest_held_title_tier >= tier_county
+	}
+
+	immediate = {
+		set_variable = {
+			name = lord_ruler_attention
+			value = 0
+		}
+
+		# Grant starting metal supplies to Allomancers
+		if = {
+			limit = {
+				is_allomancer_trigger = yes
+				is_noble_scadrian_trigger = yes
+			}
+			add_character_modifier = {
+				modifier = metal_reserves_abundant
+				years = 2
+			}
+		}
+		else_if = {
+			limit = {
+				is_allomancer_trigger = yes
+				is_skaa_trigger = yes
+			}
+			add_character_modifier = {
+				modifier = metal_reserves_low
+				years = 1
+			}
+		}
+		else_if = {
+			limit = {
+				is_allomancer_trigger = yes
+			}
+			add_character_modifier = {
+				modifier = metal_reserves_abundant
+				years = 2
+			}
+		}
+	}
+}

lords_of_ash/events/metal_supply_events.txt

@@ -1,4 +1,4 @@
-############################################
+############################################
 # Mistborn Mod - Metal Supply Events
 # Namespace: mistborn_metal
 ############################################
@@ -15,7 +15,7 @@ mistborn_metal.0001 = {
 	desc = mistborn_metal.0001.desc
 	theme = intrigue
 	override_background = {
-		reference = "gfx/interface/illustrations/event_scenes/corridor.dds"
+		reference = study
 	}
 
 	trigger = {
@@ -105,7 +105,7 @@ mistborn_metal.0010 = {
 	desc = mistborn_metal.0010.desc
 	theme = intrigue
 	override_background = {
-		reference = "gfx/interface/illustrations/event_scenes/corridor.dds"
+		reference = study
 	}
 
 	trigger = {
@@ -190,7 +190,7 @@ mistborn_metal.0020 = {
 	desc = mistborn_metal.0020.desc
 	theme = intrigue
 	override_background = {
-		reference = "gfx/interface/illustrations/event_scenes/corridor.dds"
+		reference = study
 	}
 
 	trigger = {
@@ -233,7 +233,7 @@ mistborn_metal.0030 = {
 	desc = mistborn_metal.0030.desc
 	theme = war
 	override_background = {
-		reference = "gfx/interface/illustrations/event_scenes/battlefield.dds"
+		reference = wilderness
 	}
 
 	trigger = {