chore: 清理后端冗余代码和数据库

- 移除 pinyin 拼音探索模块（routes/controllers/models）
- 移除 gallery、bgm、share、Level 等旧 WDKJ 模块
- 清理数据库 9 个无用集合（galleries/bgms/pinyin*等）
- 清理 38 条旧 loginlogs
- 移除旧脚本（initPinyinData/generateAudioUrls/init-knowledge-ai）
- 新增 enrich-content.js 内容丰富脚本
- 优化前端 16 页面文案，改为用户友好风格
- 修复 CSS 变量全局加载问题
- 修复排行榜公开访问问题

backend/wdkj-server/src/routes/user.js

@@ -5,7 +5,39 @@ const ApiResponse = require('../utils/response')
 const { userAuthMiddleware } = require('../middleware/auth')
 const logger = require('../utils/logger')
 
-// 应用用户认证中间件到所有路由
+/**
+ * 获取排行榜（公开接口，无需登录）
+ * GET /api/user/leaderboard
+ */
+router.get('/leaderboard', async (req, res) => {
+  try {
+    const { limit = 50, dim } = req.query
+    
+    const users = await User.getLeaderboard(dim ? parseInt(dim) : null, parseInt(limit))
+    
+    const data = users.map((u, i) => ({
+      rank: i + 1,
+      openid: u.openid,
+      nickname: u.nickName || '星辰旅者',
+      avatar: u.avatarUrl || '',
+      totalScore: u.totalScore || 0,
+      dim1Score: u.dim1Score || 0,
+      dim2Score: u.dim2Score || 0,
+      dim3Score: u.dim3Score || 0,
+      dim4Score: u.dim4Score || 0,
+      dim5Score: u.dim5Score || 0,
+      unlockedDims: u.unlockedDims || [1]
+    }))
+    
+    return ApiResponse.success(res, data)
+    
+  } catch (error) {
+    logger.error('获取排行榜失败:', error)
+    return ApiResponse.serverError(res, error.message)
+  }
+})
+
+// 应用用户认证中间件到所有路由（排行榜已在上方公开）
 router.use(userAuthMiddleware)
 
 /**
@@ -162,38 +194,6 @@ router.post('/progress', async (req, res) => {
   }
 })
 
-/**
- * 获取排行榜
- * GET /api/user/leaderboard
- */
-router.get('/leaderboard', async (req, res) => {
-  try {
-    const { limit = 50, dim } = req.query
-    
-    const users = await User.getLeaderboard(dim ? parseInt(dim) : null, parseInt(limit))
-    
-    const data = users.map((u, i) => ({
-      rank: i + 1,
-      openid: u.openid,
-      nickname: u.nickName || '星辰旅者',
-      avatar: u.avatarUrl || '',
-      totalScore: u.totalScore || 0,
-      dim1Score: u.dim1Score || 0,
-      dim2Score: u.dim2Score || 0,
-      dim3Score: u.dim3Score || 0,
-      dim4Score: u.dim4Score || 0,
-      dim5Score: u.dim5Score || 0,
-      unlockedDims: u.unlockedDims || [1]
-    }))
-    
-    return ApiResponse.success(res, data)
-    
-  } catch (error) {
-    logger.error('获取排行榜失败:', error)
-    return ApiResponse.serverError(res, error.message)
-  }
-})
-
 /**
  * 获取用户成就
  * GET /api/user/achievements