build: re-add yarn engines field with correct version

The omission of this field causes `yarn bazel run @npm2//:sync` to fail with

```
ERROR: An error occurred during the fetch of repository 'npm2':
   Traceback (most recent call last):
        File "/usr/local/google/home/alanagius/.cache/bazel/_bazel_alanagius/2fa837e4c5ce941f68b762e5f8e7dc4d/external/aspect_rules_js/npm/private/npm_translate_lock.bzl", line 112, column 21, in _npm_translate_lock_impl
                fail(msg)
Error in fail:

INFO: pnpm-lock.yaml file updated. Please run your build again.
```

.aspect/rules/external_repository_action_cache/npm_translate_lock_MzA5NzUwNzMx

@@ -2,7 +2,7 @@
 # Input hashes for repository rule npm_translate_lock(name = "npm2", pnpm_lock = "@//:pnpm-lock.yaml").
 # This file should be checked into version control along with the pnpm-lock.yaml file.
 .npmrc=-2023857461
-package.json=1044460161
-pnpm-lock.yaml=451366521
+package.json=1627560638
+pnpm-lock.yaml=-1807446371
 pnpm-workspace.yaml=1711114604
 yarn.lock=-892267542

package.json

@@ -32,6 +32,7 @@
   },
   "engines": {
     "node": "^18.19.1 || ^20.11.1 || >=22.0.0",
+    "yarn": "^4.5",
     "npm": "Please use yarn instead of NPM to install dependencies"
   },
   "author": "Angular Authors",