chore: replace unbuild with tsup for CJS compat

unbuild was not setting both module.exports and module.exports.default which hurts compatibility with CJS.  tsup uses esbuild so we'll try it out.  Unfortunately arethetypeswrong complains about Missing export = but it's not a breaking error, just unnecessary.

Author: JasonWeinzierl

build.config.ts

@@ -28,20 +28,20 @@
         "default": "./dist/index.mjs"
       },
       "require": {
-        "types": "./dist/index.d.cts",
-        "default": "./dist/index.cjs"
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.js"
       }
     }
   },
-  "main": "./dist/index.cjs",
+  "main": "./dist/index.js",
   "module": "./dist/index.mjs",
   "types": "./dist/index.d.ts",
   "files": [
     "dist",
     "docs"
   ],
   "scripts": {
-    "build": "unbuild && tsx scripts/postbuild.ts",
+    "build": "tsup",
     "lint": "eslint",
     "release": "bumpp && yarn run build",
     "test": "vitest",
@@ -77,10 +77,10 @@
     "eslint-plugin-import-x": "^4.4.0",
     "eslint-plugin-n": "^17.12.0",
     "rxjs": "^7.0.0",
+    "tsup": "^8.3.5",
     "tsx": "^4.19.2",
     "typescript": "~5.6.3",
     "typescript-eslint": "^8.12.2",
-    "unbuild": "^2.0.0",
     "vitest": "^2.1.4"
   },
   "engines": {

package.json

@@ -1,5 +1,5 @@
 import { TSESLint } from '@typescript-eslint/utils';
-import { name, version } from '../package.json' assert { type: 'json' };
+import { name, version } from '../package.json';
 import { createRecommendedConfig } from './configs/recommended';
 
 import { banObservablesRule } from './rules/ban-observables';

scripts/postbuild.ts

@@ -0,0 +1,10 @@
+import { defineConfig } from 'tsup';
+
+export default defineConfig({
+  entry: [
+    'src/index.ts',
+  ],
+  clean: true,
+  dts: true,
+  format: ['cjs', 'esm'],
+});