fix: update plugin entry to OpenClaw SDK format and improve installation docs

- Change plugin-entry.ts export to SDK-compliant object format
- Add explicit id, name, description fields
- Use register(api) method for tool registration
- Update README with correct installation steps
- Document plugin enable and gateway restart commands

ts/src/plugin-entry.ts

@@ -1,15 +1,20 @@
 import { GraphMemoryToolSchema, createGraphMemoryTool } from './runtime/core/tools/builtin/graph_memory_tool.js';
 
-export default function registerGraphMemoryPlugin(api: {
-  registerTool: (tool: {
-    name: string;
-    description: string;
-    parameters: typeof GraphMemoryToolSchema;
-    execute: (id: string, params: Record<string, unknown>) => Promise<{
-      content: Array<{ type: 'text'; text: string }>;
-    }>;
-  }) => void;
-}): void {
-  const tool = createGraphMemoryTool();
-  api.registerTool(tool);
-}
+export default {
+  id: 'graph-memory',
+  name: 'Graph Memory',
+  description: '让 AI 拥有真正的长期记忆能力 - 基于图数据库的记忆系统',
+  register(api: {
+    registerTool: (tool: {
+      name: string;
+      description: string;
+      parameters: typeof GraphMemoryToolSchema;
+      execute: (id: string, params: Record<string, unknown>) => Promise<{
+        content: Array<{ type: 'text'; text: string }>;
+      }>;
+    }) => void;
+  }): void {
+    const tool = createGraphMemoryTool();
+    api.registerTool(tool);
+  }
+};