bug: Unable to compile on client projects by ffjavascript

[brickpop]

Describe the bug
Unable to effectively use the library at all:

The current import:

const { Scalar, utils: ffutils } = require("ffjavascript/require.cjs")

Fails to work, because of the exports section on ffjavascript:

"exports": {
    "import": "./main.js",
    "require": "./build/main.cjs"
  },

However, according to the documentation, this section is expected to be used for submodules:
https://nodejs.org/api/packages.html#packages_subpath_exports

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Also, undo commit 2987698