refactor: Promote basepath to environment variable (#24445)

Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>

web/.env.example

 NEXT_PUBLIC_DEPLOY_ENV=DEVELOPMENT
 # The deployment edition, SELF_HOSTED
 NEXT_PUBLIC_EDITION=SELF_HOSTED
+# The base path for the application
+NEXT_PUBLIC_BASE_PATH=
 # The base URL of console application, refers to the Console base URL of WEB service if console domain is
 # different from api or web app domain.
 # example: http://cloud.dify.ai/console/api

web/Dockerfile

 RUN corepack enable
 ENV PNPM_HOME="/pnpm"
 ENV PATH="$PNPM_HOME:$PATH"
+ENV NEXT_PUBLIC_BASE_PATH=
 
 
 # install packages

web/docker/entrypoint.sh

 
 export NEXT_PUBLIC_DEPLOY_ENV=${DEPLOY_ENV}
 export NEXT_PUBLIC_EDITION=${EDITION}
+export NEXT_PUBLIC_BASE_PATH=${NEXT_PUBLIC_BASE_PATH}
 export NEXT_PUBLIC_API_PREFIX=${CONSOLE_API_URL}/console/api
 export NEXT_PUBLIC_PUBLIC_API_PREFIX=${APP_API_URL}/api
 export NEXT_PUBLIC_MARKETPLACE_API_PREFIX=${MARKETPLACE_API_URL}/api/v1

web/utils/var-basePath.js

 // export basePath to next.config.js
 // same as the one exported from var.ts
 module.exports = {
-  basePath: '',
+  basePath: process.env.NEXT_PUBLIC_BASE_PATH || '',
   assetPrefix: '',
 }