feat(HAI-081): add changesets-based automated versioning and release workflow

- Install and configure @changesets/cli with commit/access settings
- Create version PR workflow (.github/workflows/version.yml) for automated version bumps
- Update existing release and test-release workflows with version validation
- Add example changeset and version tests for CI verification
- Add RELEASING.md guide and update README with versioning documentation

.changeset/README.md

@@ -0,0 +1,8 @@
+# Changesets
+
+Hello and welcome! This folder has been automatically generated by `@changesets/cli`, a build tool that works
+with multi-package repos, or single-package repos to help you version and publish your code. You can
+find the full documentation for it [in our repository](https://github.com/changesets/changesets).
+
+We have a quick list of common questions to get you started engaging with this project in
+[our documentation](https://github.com/changesets/changesets/blob/main/docs/common-questions.md).

.changeset/add-auto-versioning.md

@@ -0,0 +1,5 @@
+---
+"hai": minor
+---
+
+Add automated versioning pipeline using changesets. Developers now add changeset files to describe changes, and a CI workflow automatically opens version PRs that bump versions and generate changelogs.

.changeset/config.json

@@ -0,0 +1,11 @@
+{
+  "$schema": "https://unpkg.com/@changesets/config@3.1.3/schema.json",
+  "changelog": "@changesets/cli/changelog",
+  "commit": false,
+  "fixed": [],
+  "linked": [],
+  "access": "restricted",
+  "baseBranch": "main",
+  "updateInternalDependencies": "patch",
+  "ignore": []
+}