prepare v0.15.0 (#512)

Author: bgentry

CHANGELOG.md

@@ -7,10 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [v0.15.0] - 2026-02-26
+
 ### Changed
 
 - Upgrade supported Go versions to 1.25 and 1.26, and update CI accordingly. [PR #508](https://github.com/riverqueue/riverui/pull/508).
-- Upgrade River to v0.31.0 and River Pro to v0.22.0.  [PR #XXX](https://github.com/riverqueue/riverui/pull/XXX).
+- Upgrade River to v0.31.0 and River Pro to v0.22.0. [PR #511](https://github.com/riverqueue/riverui/pull/511).
 - Numerous dependency upgrades.
 
 ### Fixed