♻️ 大幅重构，拆分模块，增加一些MCP相关限制

tests/test_config_and_messages.py

@@ -0,0 +1,31 @@
+# ruff: noqa: I001
+import unittest
+
+from pydantic import ValidationError
+
+import tests.bootstrap  # noqa: F401
+from nonebot_plugin_llmchat.config import MCPServerConfig, PresetConfig, ScopedConfig
+from nonebot_plugin_llmchat.message_utils import pop_reasoning_content
+
+
+def assert_validation_error(factory):
+    try:
+        factory()
+    except ValidationError:
+        return
+    raise AssertionError("expected ValidationError")
+
+
+class ConfigurationTests(unittest.TestCase):
+    def test_rejects_duplicate_presets(self):
+        preset = PresetConfig(name="same", api_base="x", api_key="x", model_name="x")
+        assert_validation_error(lambda: ScopedConfig(api_presets=[preset, preset]))
+
+    def test_mcp_requires_exactly_one_transport_target(self):
+        assert_validation_error(MCPServerConfig)
+        assert_validation_error(lambda: MCPServerConfig(command="cmd", url="https://example.invalid"))
+
+    def test_reasoning_tag_is_removed(self):
+        reply, reasoning = pop_reasoning_content("<think>secret</think>answer")
+        assert reply == "answer"
+        assert reasoning == "secret"