Implement production vertical slice foundation

game/domain/dive/battery_snapshot.gd

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+class_name BatterySnapshot
+extends RefCounted
+
+var remaining_kwh: float
+var maximum_kwh: float
+var ratio: float
+var current_power_kw: float
+var endurance_minutes: float
+
+
+func _init(
+	p_remaining_kwh: float,
+	p_maximum_kwh: float,
+	p_current_power_kw: float
+) -> void:
+	remaining_kwh = p_remaining_kwh
+	maximum_kwh = p_maximum_kwh
+	ratio = remaining_kwh / maximum_kwh if maximum_kwh > 0.0 else 0.0
+	current_power_kw = p_current_power_kw
+	endurance_minutes = (
+		remaining_kwh / current_power_kw * 60.0 if current_power_kw > 0.0 else INF
+	)