fix: support Windows launcher import paths

bin/import-specifier.test.mjs

@@ -0,0 +1,13 @@
+import assert from 'node:assert/strict'
+import test from 'node:test'
+
+import { getDistImportSpecifier } from './import-specifier.mjs'
+
+test('builds a file URL import specifier for dist/cli.mjs', () => {
+  const specifier = getDistImportSpecifier('C:\\repo\\bin')
+
+  assert.equal(
+    specifier,
+    'file:///C:/repo/dist/cli.mjs',
+  )
+})