feat: 后台管理系统完整重构 + 前后台数据联通

- 后台全面引入 Naive UI 组件库，统一 UI 规范
- 前台 usePublicApi 切换到 API 调用（GET /api/content/[key]）
- 前后台数据源统一（site_content 表）
- 产品线统一管理（tour/camp/course 三套编辑器）
- 产品数据归一化（itinerary/faq/pricing 格式统一）
- 表单提交 API 改写入 submissions 表
- 新增 submissions 标记已读 API
- site-content PUT 支持 upsert
- 修复前台 bug（stories 路由冲突、占位符警告、selector breadcrumb）
- 消除 PageHero 类型警告（useSEO reactive 修复）
- 25 个前台页面全部 HTTP 200，展示效果不变

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/api/admin/site-content/item.get.js

@@ -0,0 +1,51 @@
+import { eq } from 'drizzle-orm'
+import { useDB, schema } from '../../../utils/db.js'
+import { requireAdmin } from '../../../utils/auth.js'
+
+/**
+ * 从 site_content JSON 数组中读取单个条目
+ * GET /api/admin/site-content/item?key=products&path=versions&index=0
+ */
+export default defineEventHandler(async (event) => {
+  requireAdmin(event)
+  const query = getQuery(event)
+  const { key, path, index } = query
+
+  if (!key) throw createError({ statusCode: 422, message: 'key 参数必填' })
+
+  const db = useDB()
+  const row = db.select().from(schema.siteContent).where(eq(schema.siteContent.key, key)).get()
+  if (!row) throw createError({ statusCode: 404, message: '未找到配置' })
+
+  const data = JSON.parse(row.data)
+
+  // 如果指定了 path，在嵌套对象中取数组
+  let arr = data
+  if (path) {
+    arr = path.split('.').reduce((obj, k) => obj?.[k], data)
+  }
+
+  if (!Array.isArray(arr)) {
+    throw createError({ statusCode: 422, message: `${path || 'root'} 不是数组` })
+  }
+
+  if (index !== undefined) {
+    const idx = Number(index)
+    if (idx < 0 || idx >= arr.length) throw createError({ statusCode: 404, message: '索引超出范围' })
+    return { item: arr[idx], index: idx, total: arr.length }
+  }
+
+  // 不传 index 就返回列表概要（只取关键字段，不返回大块内容）
+  const items = arr.map((item, i) => ({
+    _index: i,
+    id: item.id || '',
+    name: item.name || item.title || '',
+    tag: item.tag || item.line || '',
+    days: item.days || '',
+    nights: item.nights || '',
+    subtitle: item.subtitle || '',
+    audience: item.audience || '',
+  }))
+
+  return { items, total: arr.length }
+})

server/api/admin/site-content/item.put.js

@@ -0,0 +1,47 @@
+import { eq } from 'drizzle-orm'
+import { useDB, schema } from '../../../utils/db.js'
+import { requireAdmin } from '../../../utils/auth.js'
+
+/**
+ * 更新 site_content JSON 数组中的单个条目
+ * PUT /api/admin/site-content/item
+ * body: { key, path, index, item }
+ */
+export default defineEventHandler(async (event) => {
+  requireAdmin(event)
+  const body = await readBody(event)
+  const { key, path, index, item } = body
+
+  if (!key || index === undefined || !item) {
+    throw createError({ statusCode: 422, message: 'key, index, item 参数必填' })
+  }
+
+  const db = useDB()
+  const row = db.select().from(schema.siteContent).where(eq(schema.siteContent.key, key)).get()
+  if (!row) throw createError({ statusCode: 404, message: '未找到配置' })
+
+  const data = JSON.parse(row.data)
+  const idx = Number(index)
+
+  // 定位到目标数组
+  if (path) {
+    const keys = path.split('.')
+    let parent = data
+    for (let i = 0; i < keys.length - 1; i++) parent = parent[keys[i]]
+    const lastKey = keys[keys.length - 1]
+    if (!Array.isArray(parent[lastKey])) throw createError({ statusCode: 422, message: 'path 不是数组' })
+    if (idx < 0 || idx >= parent[lastKey].length) throw createError({ statusCode: 404, message: '索引超出范围' })
+    parent[lastKey][idx] = item
+  } else {
+    if (!Array.isArray(data)) throw createError({ statusCode: 422, message: 'root 不是数组' })
+    if (idx < 0 || idx >= data.length) throw createError({ statusCode: 404, message: '索引超出范围' })
+    data[idx] = item
+  }
+
+  db.update(schema.siteContent)
+    .set({ data: JSON.stringify(data), updatedAt: new Date().toISOString() })
+    .where(eq(schema.siteContent.key, key))
+    .run()
+
+  return { success: true }
+})