重构整个插件系统，尝试恢复可启动性，新增插件系统maibot-plugin-sdk依赖

src/plugins/built_in/knowledge/plugin.py

@@ -0,0 +1,39 @@
+"""LPMM 知识库搜索插件 — 新 SDK 版本
+
+提供 LLM 可调用的知识库搜索工具。
+"""
+
+from maibot_sdk import MaiBotPlugin, Tool
+from maibot_sdk.types import ToolParameterInfo, ToolParamType
+
+
+class KnowledgePlugin(MaiBotPlugin):
+    """LPMM 知识库插件"""
+
+    @Tool(
+        "lpmm_search_knowledge",
+        description="从知识库中搜索相关信息，如果你需要知识，就使用这个工具",
+        parameters=[
+            ToolParameterInfo(name="query", param_type=ToolParamType.STRING, description="搜索查询关键词", required=True),
+            ToolParameterInfo(name="limit", param_type=ToolParamType.INTEGER, description="希望返回的相关知识条数，默认5", required=False, default=5),
+        ],
+    )
+    async def handle_lpmm_search_knowledge(self, query: str = "", limit: int = 5, **kwargs):
+        """执行知识库搜索"""
+        if not query:
+            return {"type": "info", "id": "", "content": "未提供搜索关键词"}
+
+        try:
+            limit_value = max(1, int(limit))
+        except (TypeError, ValueError):
+            limit_value = 5
+
+        result = await self.ctx.call_capability("knowledge.search", query=query, limit=limit_value)
+        if result and result.get("success"):
+            content = result.get("content", f"你不太了解有关{query}的知识")
+            return {"type": "lpmm_knowledge", "id": query, "content": content}
+        return {"type": "info", "id": query, "content": f"知识库搜索失败: {result}"}
+
+
+def create_plugin():
+    return KnowledgePlugin()