feat: 新增 HTTP MCP Server，让 AI Agent 接入选菜

新增 packages/mcp，基于 Streamable HTTP 暴露菜谱库能力，复用 packages/cook 的选菜算法：recommend_recipes 按现有食材推荐，search_recipes 条件检索，check_incompatible 食材相克，get_recipe 菜谱详情。容器内与 nginx 共存，映射 2230 端口供 Agent 连接。

packages/mcp/package.json

@@ -0,0 +1,25 @@
+{
+  "name": "@cook/mcp",
+  "type": "module",
+  "version": "0.1.0",
+  "private": true,
+  "description": "食用手册 MCP Server —— 以 HTTP 暴露菜谱检索能力，供 AI Agent 选菜",
+  "license": "MIT",
+  "scripts": {
+    "build": "unbuild",
+    "dev": "tsx src/index.ts",
+    "start": "node dist/index.mjs"
+  },
+  "dependencies": {
+    "@modelcontextprotocol/sdk": "^1.32.1",
+    "@yunyoujun/cook": "workspace:*",
+    "express": "^5.2.1",
+    "zod": "^4.6.7"
+  },
+  "devDependencies": {
+    "@types/express": "^5.0.6",
+    "@types/node": "^25.9.5",
+    "tsx": "^4.23.12",
+    "unbuild": "^3.6.1"
+  }
+}