fix: register_agent decorator NameError (AstrBotDevs#5765)

* fix: 修改 register_agent 以避免运行时导入 AstrAgentContext

* test: improve register_agent test robustness

- Add fixture for llm_tools cleanup to avoid test interference
- Use multiple import patterns to make guard more robust to refactors
- Add assertion to verify decorated coroutine is wired as handoff handler

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* 删除测试文件: 移除 register_agent 装饰器的运行时行为测试

---------

Co-authored-by: whatevertogo <whatevertogo@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Soulter <905617992@qq.com>

Author: 3 people

astrbot/core/star/register/star_handler.py

@@ -2,7 +2,7 @@
 
 import re
 from collections.abc import AsyncGenerator, Awaitable, Callable
-from typing import TYPE_CHECKING, Any
+from typing import Any
 
 import docstring_parser
 
@@ -15,9 +15,6 @@
 from astrbot.core.provider.func_tool_manager import PY_TO_JSON_TYPE, SUPPORTED_TYPES
 from astrbot.core.provider.register import llm_tools
 
-if TYPE_CHECKING:
-    from astrbot.core.astr_agent_context import AstrAgentContext
-
 from ..filter.command import CommandFilter
 from ..filter.command_group import CommandGroupFilter
 from ..filter.custom_filter import CustomFilterAnd, CustomFilterOr
@@ -649,15 +646,15 @@ def llm_tool(self, *args, **kwargs):
         kwargs["registering_agent"] = self
         return register_llm_tool(*args, **kwargs)
 
-    def __init__(self, agent: Agent[AstrAgentContext]) -> None:
+    def __init__(self, agent: Agent[Any]) -> None:
         self._agent = agent
 
 
 def register_agent(
     name: str,
     instruction: str,
     tools: list[str | FunctionTool] | None = None,
-    run_hooks: BaseAgentRunHooks[AstrAgentContext] | None = None,
+    run_hooks: BaseAgentRunHooks[Any] | None = None,
 ):
     """注册一个 Agent
 
@@ -671,12 +668,12 @@ def register_agent(
     tools_ = tools or []
 
     def decorator(awaitable: Callable[..., Awaitable[Any]]):
-        AstrAgent = Agent[AstrAgentContext]
+        AstrAgent = Agent[Any]
         agent = AstrAgent(
             name=name,
             instructions=instruction,
             tools=tools_,
-            run_hooks=run_hooks or BaseAgentRunHooks[AstrAgentContext](),
+            run_hooks=run_hooks or BaseAgentRunHooks[Any](),
         )
         handoff_tool = HandoffTool(agent=agent)
         handoff_tool.handler = awaitable