feat: bundle provider auth plugins

Co-authored-by: ItzR3NO <ItzR3NO@users.noreply.github.com>

docs/cli/plugins.md

@@ -25,6 +25,9 @@ clawdbot plugins update <id>
 clawdbot plugins update --all
 ```
 
+Bundled plugins ship with Clawdbot but start disabled. Use `plugins enable` to
+activate them.
+
 ### Install
 
 ```bash