fix: use prepack instead of prepublishOnly

prepack runs on both npm publish and npm pack (and when installing from
git/tarball), whereas prepublishOnly only runs on npm publish. Since dist/
is gitignored, installing directly from git would produce a broken package
without this change.

Addresses CodeRabbit nitpick comment on PR #36

Author: bendtherules

package.json

@@ -70,7 +70,7 @@
     "check:jsdoc-coverage": "bun scripts/check-jsdoc-coverage.mjs",
     "lint": "bun --bun eslint .",
     "typecheck": "tsc --noEmit",
-    "prepublishOnly": "bun run build"
+    "prepack": "bun run build"
   },
   "type": "module",
   "version": "0.8.0"