fix: restore package export-map contract test

This test validates the package.json exports field, not runtime code.
Its Istanbul fingerprint is empty, making it trivially "subsumed" by
the coverage analysis — but no integration test checks the export map.

Author: thymikee

src/__tests__/package-exports.test.ts

@@ -0,0 +1,32 @@
+import fs from 'node:fs';
+import path from 'node:path';
+import { test } from 'vitest';
+import assert from 'node:assert/strict';
+
+test('package exports only supported public subpaths', () => {
+  const pkg = JSON.parse(fs.readFileSync(path.join(process.cwd(), 'package.json'), 'utf8')) as {
+    exports: Record<string, unknown>;
+  };
+
+  const supportedSubpaths = [
+    '.',
+    './io',
+    './artifacts',
+    './metro',
+    './batch',
+    './remote-config',
+    './install-source',
+    './android-adb',
+    './android-snapshot-helper',
+    './contracts',
+    './selectors',
+    './finders',
+  ];
+
+  for (const subpath of supportedSubpaths) {
+    assert.equal(pkg.exports[subpath] !== undefined, true, `${subpath} should be exported`);
+  }
+
+  assert.equal(pkg.exports['./android-apps'], undefined);
+  assert.equal(pkg.exports['./daemon'], undefined);
+});