chore: remove dead debug code — isDevMode, debug CSS, __DEV__ flag

miniprogram/utils/page.js

@@ -16,10 +16,4 @@ function navigateBack(fallbackUrl) {
   })
 }
 
-/** Check if dev mode is enabled */
-function isDevMode() {
-  var config = require('../config/env')
-  return config.__DEV__ || false
-}
-
-module.exports = { getStatusBarHeight: getStatusBarHeight, navigateBack: navigateBack, isDevMode: isDevMode }
+module.exports = { getStatusBarHeight: getStatusBarHeight, navigateBack: navigateBack }