Add supply auto-purchase and preserve save recovery state

tests/fixtures/pre_auto_purchase_runtime.gd

@@ -0,0 +1,8 @@
+extends RefCounted
+
+## A genuine pre-v14 fixture must have no player automatic purchase intent.
+static func strip_empty(data: Dictionary) -> void:
+	assert(data.has(&"auto_purchase_plans"))
+	var plans: Dictionary = data[&"auto_purchase_plans"]
+	assert(plans[&"version"] == 1 and (plans[&"plans"] as Array).is_empty())
+	data.erase(&"auto_purchase_plans")

tests/fixtures/pre_auto_purchase_runtime.gd.uid

@@ -0,0 +1 @@
+uid://dqjyetek8aurm

tests/fixtures/pre_upkeep_runtime.gd

@@ -2,6 +2,7 @@ extends RefCounted
 
 ## Build a genuine pre-v10 fixture only when no upkeep ledger history exists.
 static func strip_empty_upkeep(data: Dictionary) -> void:
+	preload("res://tests/fixtures/pre_auto_purchase_runtime.gd").strip_empty(data)
 	for entry: Dictionary in data[&"economy"][&"entries"]:
 		assert(String(entry.get(&"category", "")) not in ["MAINTENANCE_ACCRUAL", "MAINTENANCE_PAYMENT"])
 	data.erase(&"weather")