chore: release 4.15.2

[nhobes]

One item: vertical_menu joins the showcase registry (#693) - the wave's one holdout. Publishing lets petal.build's menus page swap to assign_showcase and the MCP pick up the Northwind flagship + standalone examples. Suite 1813/0.

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR prepares the 4.15.2 release by synchronizing the package version and changelog.

• Updates the Mix project version from 4.15.1 to 4.15.2.
• Publishes the unreleased changelog section as the 2026-08-25 release.

Confidence Score: 5/5

The PR appears safe to merge with consistent release metadata and no identified defects.

The package version and changelog release heading agree, follow the repository’s established release pattern, and require no additional coordinated source changes.

Important Files Changed

Filename	Overview
mix.exs	Updates the package version to 4.15.2 consistently with the release tooling and changelog.
CHANGELOG.md	Converts the unreleased section into a correctly formatted 4.15.2 release entry dated 2026-08-25.

_{Reviews (1): Last reviewed commit: "chore: release 4.15.2" | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.41%. Comparing base (d2dcfc0) to head (2bc3ed5).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #694   +/-   ##
=======================================
  Coverage   95.41%   95.41%           
=======================================
  Files         163      163           
  Lines        8078     8078           
=======================================
  Hits         7708     7708           
  Misses        370      370           

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