feat(core/agent): 添加 Step 和 LoopResult 数据类

保真 TRM4 算法 #11，Step 新增 call_id 字段。

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/agent/types.py

@@ -0,0 +1,31 @@
+"""AgentLoop 数据类型。"""
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from typing import Any
+
+
+@dataclass
+class Step:
+    """Agent 单步决策记录。"""
+
+    thought: str
+    reflect: dict[str, Any]
+    plan: dict[str, Any]
+    tool_call: dict[str, Any]
+    tool_output: str
+    raw_content: str
+    call_id: str
+
+
+@dataclass
+class LoopResult:
+    """AgentLoop 完整运行结果。"""
+
+    result: dict[str, Any] | None = None
+    steps: list[Step] = field(default_factory=list)
+    steps_used: int = 0
+    token_usage: dict[str, int] = field(
+        default_factory=lambda: {"prompt_tokens": 0, "completion_tokens": 0}
+    )
+    stop_reason: str = "finished"