docs: fix SPRINTS header and CHANGELOG footer to v0.24

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -793,4 +793,4 @@ Three-panel layout: sessions sidebar, chat area, workspace panel.
 
 ---
 
-*Last updated: v0.23, April 3, 2026 | Tests: 415*
+*Last updated: v0.24, April 3, 2026 | Tests: 415*

SPRINTS.md

@@ -1,6 +1,6 @@
 # Hermes Web UI -- Forward Sprint Plan
 
-> Current state: v0.23 | 415 tests | Daily driver ready
+> Current state: v0.24 | 415 tests | Daily driver ready
 > This document plans the path from here to two targets:
 >
 > Target A: 1:1 feature parity with the Hermes CLI (everything you can do from the