Direct 回合链路引入 typed 错误数据模型

- 新增 direct_turn_error 深模块：DirectTurnError 按变体各带字段，调用级拒绝与回合级失败分开
- 原生失败分类 DirectCodexNativeKind 由结构化前缀读入，事件载荷 kind 与旧口径逐条对齐
- 模型调用失败按平台 LlmError 分支投影成 DirectModelCallKind，反馈/重试/摘要/建议改由类型判定
- 跨进程边界仍由 Display 序列化成字符串，Rust 侧不再解析该字符串

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

@@ -34,6 +34,7 @@ mod direct_thread_wire;
 mod direct_tool_bridge;
 mod direct_tool_calls;
 mod direct_tools_mcp;
+mod direct_turn_error;
 mod direct_turn_failure;
 mod direct_turn_metrics;
 mod direct_turn_stream;
@@ -73,6 +74,7 @@ pub(crate) use direct_thread_wire::*;
 pub(crate) use direct_tool_bridge::*;
 pub(crate) use direct_tool_calls::*;
 pub(crate) use direct_tools_mcp::*;
+pub(crate) use direct_turn_error::*;
 pub(crate) use direct_turn_failure::*;
 pub(crate) use direct_turn_metrics::*;
 pub(crate) use direct_turn_stream::*;