fix(agent-author): require plugin version bump after agent changes

## Why
Same gap as skill-author: no instruction to bump the plugin version after
creating or modifying an agent inside a plugin.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/kyberforge/.claude-plugin/plugin.json

@@ -8,5 +8,5 @@
   "keywords": [],
   "license": "MIT",
   "name": "kyberforge",
-  "version": "1.0.4"
+  "version": "1.0.5"
 }