need a new build mode

[FanetheDivine]

Goals

1. to build static pages from a common Next project that uses server actions and other features.

Non-Goals

Background

when using Next in Tauri , a project must be built in mode export so that many of Next's features are disabled. The web site built from that project is not so good

Proposal

in next.config.js, the attribute output can be set as split and the built project has a config file to set what server url is