chore: release v0.15.1 (#2256)

<!-- CURSOR_SUMMARY -->
> [!NOTE]
> Finalize 0.15.1 release by updating CHANGELOG and bumping VERSION from
-dev to stable.
> 
> - **Release 0.15.1**:
>   - Update `CHANGELOG.md` heading from `Unreleased` to `0.15.1`.
>   - Bump `VERSION` from `0.15.1-dev` to `0.15.1`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
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<!-- /CURSOR_SUMMARY -->

Author: snakster

CHANGELOG.md

@@ -20,7 +20,7 @@ Given a version number `MAJOR.MINOR.PATCH`, we increment the:
 - Backward compatibility in versions `0.0.z` is **not guaranteed** when `z` is increased.
 - Backward compatibility in versions `0.y.z` is **not guaranteed** when `y` is increased.
 
-## Unreleased
+## 0.15.1
 
 ### Added
 

VERSION

@@ -1 +1 @@
-0.15.1-dev
+0.15.1