交付类工具的裸 cause 补工具前缀

- delivery_status 的 StatusUnavailable 文案改为「交付状态读取失败：{cause}」
- register_delivery_contract 的 ContractRejected 文案改为「登记交付合同失败：{cause}」
- update_plan 的 PlanRejected 文案改为「更新计划失败：{cause}」
- 这些 cause 是 direct_delivery 的内部机器码（如 delivery-status-worker-exited），原来单独回给模型时没有任何工具上下文

apps/ai-game-creator-shell/src-tauri/src/agent/tool/delivery_status/error.rs

@@ -26,7 +26,7 @@ impl ToolFailure for DeliveryStatusError {
         match self {
             Self::ArgumentsNotAccepted => "交付状态工具不接受参数。".to_string(),
             Self::Gate(rejection) => rejection.to_user_msg(),
-            Self::StatusUnavailable { cause } => cause.to_string(),
+            Self::StatusUnavailable { cause } => format!("交付状态读取失败：{cause}"),
         }
     }
 

apps/ai-game-creator-shell/src-tauri/src/agent/tool/register_delivery_contract/error.rs

@@ -24,7 +24,7 @@ impl ToolFailure for RegisterDeliveryContractError {
     fn to_user_msg(&self) -> String {
         match self {
             Self::Gate(rejection) => rejection.to_user_msg(),
-            Self::ContractRejected { cause } => cause.to_string(),
+            Self::ContractRejected { cause } => format!("登记交付合同失败：{cause}"),
         }
     }
 

apps/ai-game-creator-shell/src-tauri/src/agent/tool/update_plan/error.rs

@@ -23,7 +23,7 @@ impl ToolFailure for UpdatePlanError {
     fn to_user_msg(&self) -> String {
         match self {
             Self::Gate(rejection) => rejection.to_user_msg(),
-            Self::PlanRejected { cause } => cause.to_string(),
+            Self::PlanRejected { cause } => format!("更新计划失败：{cause}"),
         }
     }