Implement production vertical slice foundation

game/domain/dive/tool_power_demand.gd

@@ -0,0 +1,18 @@
+class_name ToolPowerDemand
+extends RefCounted
+
+var tool_id: StringName
+var effective_power_kw: float
+
+
+func _init(p_tool_id: StringName, p_effective_power_kw: float) -> void:
+	tool_id = p_tool_id
+	effective_power_kw = p_effective_power_kw
+
+
+func validation_error() -> String:
+	if tool_id.is_empty():
+		return "tool_id is empty"
+	if not is_finite(effective_power_kw) or effective_power_kw < 0.0:
+		return "tool power must be finite and non-negative"
+	return ""