feat(mana): balance.json mana_heat/infinite_spells 配置 + SettingsManager getters

scripts/autoloads/settings_manager.gd

@@ -34,6 +34,8 @@ func complete_ftue(chosen_difficulty: int) -> void:
 var _MULTS: Dictionary = {}    # key → [初学者, 标准, 挑战]
 var _BOSS_HP: Dictionary = {}  # 原型→基础血量
 var _AETHER_THRESHOLDS: Array = []   # [[到达波次, 碎片], ...] 升序
+var _MANA_HEAT: Dictionary = {"per_cast": 0.01, "decay_per_sec": 0.1, "max": 1.0}
+var _INFINITE: Dictionary = {"hp_per_shot": 1.0, "hp_cost_cap_ratio": 0.15}
 
 const BALANCE_JSON: String = "res://data/balance.json"
 
@@ -61,6 +63,12 @@ func aether_for_wave(wave: int) -> int:
 			result = maxi(result, int(entry[1]))   # 取 ≤wave 阶梯中的最大值，容忍无序表（设计师手填不必排序）
 	return result
 
+func mana_heat_per_cast() -> float:   return float(_MANA_HEAT.get("per_cast", 0.01))
+func mana_heat_decay() -> float:      return float(_MANA_HEAT.get("decay_per_sec", 0.1))
+func mana_heat_max() -> float:        return float(_MANA_HEAT.get("max", 1.0))
+func infinite_hp_per_shot() -> float: return float(_INFINITE.get("hp_per_shot", 1.0))
+func hp_cost_cap_ratio() -> float:    return float(_INFINITE.get("hp_cost_cap_ratio", 0.15))
+
 ## 数据驱动：加载 balance.json（难度乘子 + Boss 血量）
 func _load_balance() -> void:
 	if not FileAccess.file_exists(BALANCE_JSON):
@@ -77,6 +85,12 @@ func _load_balance() -> void:
 		_BOSS_HP = data["boss_hp"]
 	if data.has("aether_thresholds") and data["aether_thresholds"] is Array:
 		_AETHER_THRESHOLDS = data["aether_thresholds"]
+	if data.has("mana_heat") and data["mana_heat"] is Dictionary:
+		for k in data["mana_heat"]:
+			_MANA_HEAT[k] = data["mana_heat"][k]
+	if data.has("infinite_spells") and data["infinite_spells"] is Dictionary:
+		for k in data["infinite_spells"]:
+			_INFINITE[k] = data["infinite_spells"][k]
 
 func difficulty_name() -> String:
 	return ["DIFF_BEGINNER", "DIFF_STANDARD", "DIFF_CHALLENGE"][difficulty]