refactor: move openai_agents to _internal/agents

Move the openai-agents SDK integration from core/agent/runners/openai_agents
to _internal/agents/openai_agents to follow the internal implementation pattern.

astrbot/_internal/agents/__init__.py

@@ -0,0 +1,12 @@
+"""AstrBot internal agents module.
+
+This module contains internal agent implementations.
+For public API, use astrbot.api.
+"""
+
+from .openai_agents import OpenAIAgentsRunner, astrbot_tool_to_agents_tool
+
+__all__ = [
+    "OpenAIAgentsRunner",
+    "astrbot_tool_to_agents_tool",
+]

astrbot/_internal/agents/openai_agents/__init__.py

@@ -5,7 +5,7 @@ allowing AstrBot to leverage the openai-agents Agent implementation
 while using its existing tool and provider infrastructure.
 
 Usage:
-    from astrbot.core.agent.runners.openai_agents import OpenAIAgentsRunner
+    from astrbot._internal.agents import OpenAIAgentsRunner
 
     runner = OpenAIAgentsRunner(agent_config)
     async for response in runner.run():

astrbot/_internal/agents/openai_agents/runner.py

@@ -15,13 +15,12 @@ from agents.run_config import RunConfig
 from astrbot.core.agent.hooks import BaseAgentRunHooks
 from astrbot.core.agent.run_context import ContextWrapper, TContext
 from astrbot.core.agent.runners.base import AgentState, BaseAgentRunner
-from astrbot.core.agent.runners.openai_agents.tool_adapter import (
-    astrbot_tool_to_agents_tool,
-)
 from astrbot.core.agent.tool import FunctionTool
 from astrbot.core.provider.entities import LLMResponse
 from astrbot.core.provider.func_tool_manager import FunctionToolManager
 
+from .tool_adapter import astrbot_tool_to_agents_tool
+
 
 class OpenAIAgentsRunner(BaseAgentRunner[TContext]):
     """An agent runner that uses the openai-agents library.