feat: 小程序移除管理后台入口，新增admin-web前端项目

将管理后台功能从微信小程序中剥离，独立为Vue.js前端项目admin-web

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

admin-web/vue.config.js

@@ -0,0 +1,26 @@
+const { defineConfig } = require('@vue/cli-service')
+
+module.exports = defineConfig({
+  transpileDependencies: true,
+  lintOnSave: false,
+  devServer: {
+    port: 8080,
+    host: '0.0.0.0',
+    historyApiFallback: true,
+    proxy: {
+      '/api': {
+        target: 'http://127.0.0.1:5000',
+        changeOrigin: true,
+        ws: false,
+        logLevel: 'debug',
+        onError(err, req, res) {
+          console.error('[proxy error]', req && req.url, err && err.message)
+          if (res && !res.headersSent) {
+            res.writeHead(502, { 'Content-Type': 'application/json; charset=utf-8' })
+            res.end(JSON.stringify({ code: -1, message: '后端代理失败，请确认 Flask 已在 5000 端口运行：' + (err && err.message) }))
+          }
+        }
+      }
+    }
+  }
+})