feat: 新增「文档」菜单（使用指南 + 接口文档）

- backend/docs/GUIDE.md：使用指南，每功能一句话讲清
  「是什么→怎么用→实用技巧」（快速开始 3 步、流水线快速上手配置、
  GitOps 概念与用法、AI 助手/批量发布/Jenkins/构建节点/工具/
  飞书通知/用户 LDAP/常见问题 FAQ）
- backend/docs/API.md：接口文档（opsx-sec 骨架：通用约定/模块
  索引表/重点端点 curl 示例/状态码速查）
- GET /api/docs：文档 embed 进二进制，运行目录 docs/ 优先可热更新
- /docs 页面：使用指南/接口文档切换 + 左侧目录锚点导航 +
  markdown 渲染（marked + gfm-heading-id，深浅主题适配排版）
- 侧边栏系统组新增「文档」入口（第一位）

frontend/package-lock.json

@@ -44,6 +44,8 @@
         "embla-carousel-react": "^8.6.0",
         "input-otp": "^1.5.0",
         "lucide-react": "^0.562.0",
+        "marked": "^18.1.2",
+        "marked-gfm-heading-id": "^4.1.4",
         "next-themes": "^0.4.6",
         "react": "^19.3.1",
         "react-day-picker": "^9.14.0",
@@ -3650,23 +3652,6 @@
         "acorn": "^6.0.0 || ^7.0.0 || ^8.0.0"
       }
     },
-    "node_modules/ajv": {
-      "version": "8.20.0",
-      "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.20.0.tgz",
-      "integrity": "sha512-Thbli+OlOj+iMPYFBVBfJ3OmCAnaSyNn4M1vz9T6Gka5Jt9ba/HIR56joy65tY6kx/FCF5VXNB819Y7/GUrBGA==",
-      "extraneous": true,
-      "license": "MIT",
-      "dependencies": {
-        "fast-deep-equal": "^3.1.3",
-        "fast-uri": "^3.0.1",
-        "json-schema-traverse": "^1.0.0",
-        "require-from-string": "^2.0.2"
-      },
-      "funding": {
-        "type": "github",
-        "url": "https://github.com/sponsors/epoberezkin"
-      }
-    },
     "node_modules/ansi-styles": {
       "version": "4.3.0",
       "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-4.3.0.tgz",
@@ -4737,23 +4722,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/fast-uri": {
-      "version": "3.1.9",
-      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.9.tgz",
-      "integrity": "sha512-hS/0Wt3Ya043oKXs0sIxrMpKQITXhMLIrVAKKXi4gozGC9v7YRWVnXIZzjNPTO02M9BdxLCWqK1yRXgNziVyJQ==",
-      "extraneous": true,
-      "funding": [
-        {
-          "type": "github",
-          "url": "https://github.com/sponsors/fastify"
-        },
-        {
-          "type": "opencollective",
-          "url": "https://opencollective.com/fastify"
-        }
-      ],
-      "license": "BSD-3-Clause"
-    },
     "node_modules/fastq": {
       "version": "1.20.3",
       "resolved": "https://registry.npmjs.org/fastq/-/fastq-1.20.3.tgz",
@@ -4886,6 +4854,12 @@
         "node": ">=6"
       }
     },
+    "node_modules/github-slugger": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/github-slugger/-/github-slugger-2.0.0.tgz",
+      "integrity": "sha512-IaOQ9puYtjrkq7Y0Ygl9KDZnrf/aiUJYUpVf89y8kyaxbRG7Y1SrX/jaumrv81vc61+kiMempujsM3Yw7w5qcw==",
+      "license": "ISC"
+    },
     "node_modules/glob-parent": {
       "version": "6.0.2",
       "resolved": "https://registry.npmjs.org/glob-parent/-/glob-parent-6.0.2.tgz",
@@ -5136,13 +5110,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/json-schema-traverse": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/json-schema-traverse/-/json-schema-traverse-1.0.0.tgz",
-      "integrity": "sha512-NM8/P9n3XjXhIZn1lLhkFaACTOURQXjWhV4BA/RnOv8xvgqtqpAX9IO4mRQxSx1Rlo4tqzeqb0sOlruaOy3dug==",
-      "extraneous": true,
-      "license": "MIT"
-    },
     "node_modules/json-stable-stringify-without-jsonify": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/json-stable-stringify-without-jsonify/-/json-stable-stringify-without-jsonify-1.0.1.tgz",
@@ -5267,6 +5234,30 @@
         "react": "^16.5.1 || ^17.0.0 || ^18.0.0 || ^19.0.0"
       }
     },
+    "node_modules/marked": {
+      "version": "18.1.2",
+      "resolved": "https://registry.npmjs.org/marked/-/marked-18.1.2.tgz",
+      "integrity": "sha512-DfOnvLAQ6WYeWxWO1u4RyFOeqyHup6dks5PPqnoFiooU7ipRvidO/2j8plhAHIiZg574E9ZlzSjUiPMLAzFkgg==",
+      "license": "MIT",
+      "bin": {
+        "marked": "bin/marked.js"
+      },
+      "engines": {
+        "node": ">= 20"
+      }
+    },
+    "node_modules/marked-gfm-heading-id": {
+      "version": "4.1.4",
+      "resolved": "https://registry.npmjs.org/marked-gfm-heading-id/-/marked-gfm-heading-id-4.1.4.tgz",
+      "integrity": "sha512-CspnvVfHSkb/znqdPS4jUR8HtCjq3M/DnrsJCrfLBLvdrgbemmoINKpeWKQYkBiXAoBGejw0cV7xzqrPdup3WA==",
+      "license": "MIT",
+      "dependencies": {
+        "github-slugger": "^2.0.0"
+      },
+      "peerDependencies": {
+        "marked": ">=13 <19"
+      }
+    },
     "node_modules/merge2": {
       "version": "1.4.1",
       "resolved": "https://registry.npmjs.org/merge2/-/merge2-1.4.1.tgz",
@@ -6021,16 +6012,6 @@
         "decimal.js-light": "^2.4.1"
       }
     },
-    "node_modules/require-from-string": {
-      "version": "2.0.2",
-      "resolved": "https://registry.npmjs.org/require-from-string/-/require-from-string-2.0.2.tgz",
-      "integrity": "sha512-Xf0nWe6RseziFMu+Ap9biiUbmplq6S9/p+7w7YXP/JBHhrUDDUhwa+vANyubuqfZWTveU//DYVGsDG7RKL/vEw==",
-      "extraneous": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=0.10.0"
-      }
-    },
     "node_modules/resolve": {
       "version": "1.22.13",
       "resolved": "https://registry.npmjs.org/resolve/-/resolve-1.22.13.tgz",