Refresh setup screenshot to show current gx behavior in non-repo directories

The README setup image still showed legacy musafety success output, which no longer
matches current guardex CLI behavior. This update replaces the screenshot content
with the exact gx/gx setup/gx init transcript requested and adjusts the section label
so readers understand it is behavior output rather than a success-only path.

Constraint: Keep screenshot asset path stable so existing README links continue working
Rejected: Add a second screenshot file and keep the old one | increases drift and visual confusion
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: Keep docs/images/setup-success.svg synchronized with current CLI wording whenever status/setup text changes
Tested: npm test (54/54)
Not-tested: Visual rendering check in GitHub markdown UI after merge

Author: NagyVikt

README.md

@@ -70,9 +70,9 @@ That one command runs:
 5. installs local Codex + Claude gx helper skill files if missing,
 6. scans and reports final status.
 
-## Setup screenshot
+## Setup behavior screenshot
 
-![gx setup success screenshot](https://raw.githubusercontent.com/recodeecom/multiagent-safety/main/docs/images/setup-success.svg)
+![gx status/setup behavior screenshot](https://raw.githubusercontent.com/recodeecom/multiagent-safety/main/docs/images/setup-success.svg)
 
 ## Status logs screenshot