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/gallery/[id].delete.js

@@ -0,0 +1,11 @@
+import { eq } from 'drizzle-orm'
+import { useDB, schema } from '../../../utils/db.js'
+import { requireAdmin } from '../../../utils/auth.js'
+
+export default defineEventHandler(async (event) => {
+  requireAdmin(event)
+  const id = Number(getRouterParam(event, 'id'))
+  const db = useDB()
+  db.delete(schema.galleryItems).where(eq(schema.galleryItems.id, id)).run()
+  return { success: true }
+})

server/api/admin/gallery/[id].get.js

@@ -0,0 +1,12 @@
+import { eq } from 'drizzle-orm'
+import { useDB, schema } from '../../../utils/db.js'
+import { requireAdmin } from '../../../utils/auth.js'
+
+export default defineEventHandler(async (event) => {
+  requireAdmin(event)
+  const id = Number(getRouterParam(event, 'id'))
+  const db = useDB()
+  const item = db.select().from(schema.galleryItems).where(eq(schema.galleryItems.id, id)).get()
+  if (!item) throw createError({ statusCode: 404, message: '照片不存在' })
+  return item
+})

server/api/admin/gallery/[id].put.js

@@ -0,0 +1,25 @@
+import { eq } from 'drizzle-orm'
+import { useDB, schema } from '../../../utils/db.js'
+import { requireAdmin } from '../../../utils/auth.js'
+
+export default defineEventHandler(async (event) => {
+  requireAdmin(event)
+
+  const id = Number(getRouterParam(event, 'id'))
+  const body = await readBody(event)
+  const db = useDB()
+
+  const updateData = {}
+  if (body.title !== undefined) updateData.title = body.title
+  if (body.category !== undefined) updateData.category = body.category
+  if (body.location !== undefined) updateData.location = body.location
+  if (body.description !== undefined) updateData.description = body.description
+  if (body.image !== undefined) updateData.image = body.image
+  if (body.orientation !== undefined) updateData.orientation = body.orientation
+  if (body.published !== undefined) updateData.published = body.published ? 1 : 0
+  if (body.sortOrder !== undefined) updateData.sortOrder = body.sortOrder
+
+  db.update(schema.galleryItems).set(updateData).where(eq(schema.galleryItems.id, id)).run()
+
+  return { success: true }
+})