chore: add exports

[benmccann]

Leaving the main and module for now for backwards compatibility. Those could potentially be dropped with the next major

[lukeed]

I think this should be

Suggested change

	".": {
	"types": "./index.d.ts",
	"module-sync": "./lib/index.mjs",
	"require": "./lib/index.js",
	"default": "./lib/index.mjs"
	}
	".": {
	"types": "./index.d.ts",
	"module-sync": "./lib/index.mjs",
	"import": "./lib/index.mjs",
	"require": "./lib/index.js"
	},
	"./package.json": "./package.json"

right? the default fallthrough is to remain CJS, not ESM. Anything that require()s and understands exports will hit require. If it supports require(esm) then it stops at module-sync. Anything that can import will be directed to ESM

Also adding an exports map is breaking on its own.

[benmccann]

Using import/require vs require/default I think is equivalent, so I don't have a preference for one vs the other

I don't think you really need to export package.json. There was an old version of rollup-plugin-svelte that required it, but otherwise I don't think there's a great reason to do it

Ah, yeah, I guess adding an exports map could be breaking if someone were trying to access something that wasn't intended to be exposed. I forgot about that...