Add package.json#exports and fix peer dependencies

[donmccurdy]

Important change to package.json for each package here:

- "main": "dist/core.cjs",
- "module": "dist/core.js",
+ "main": "./dist/core.cjs",
+ "exports": {
+   "require": "./dist/core.cjs",
+   "default": "./dist/core.js"
+ },

module is ignored in Node.js contexts where Vite and Rollup run, so the previous ESM build was always ignored in favor of CJS. I'll publish this as a new major version, because adding exports is typically considered a breaking change.

Along with updating the peer dependencies, this avoids the dual-package-hazard problem where Vite could load a CJS copy of @gltf-transform/* for the plugin, an ESM copy for the user's transform operations, and the two wouldn't interoperate correctly.

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To do:

• fix the prerelease macros so we don't increment the version each time
• test a prerelease