chore(release): 0.5.7

Promotes the [Unreleased] async-sleep fix to a tagged release.

Fixed:
- _auto_handle_challenge no longer blocks the event loop when called
  from an async context. Polling is offloaded to a daemon thread
  named avp-challenge-{name}; sync callers behave identically.

Note: versions 0.5.3-0.5.6 were published to PyPI without CHANGELOG
entries. Going forward each release should have a corresponding
changelog section + git tag (this commit re-establishes that).

Author: creatorrmode-lead

CHANGELOG.md

@@ -2,13 +2,16 @@
 
 All notable changes to the `agentveil` SDK.
 
-## [Unreleased]
+## [0.5.7] — 2026-04-17
 
 ### Fixed
 - `_auto_handle_challenge` no longer blocks the event loop when called from an
   async context. Polling work is now offloaded to a daemon thread
   (`avp-challenge-{name}`); sync callers behave exactly as before.
 
+> Note: versions 0.5.3–0.5.6 were published to PyPI without changelog entries.
+> See git history for what changed in those releases.
+
 ## [0.5.2] — 2026-04-09
 
 ### Added

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "agentveil"
-version = "0.5.6"
+version = "0.5.7"
 description = "Python SDK for Agent Veil Protocol — reputation and identity for AI agents"
 readme = "README.md"
 requires-python = ">=3.10"