MWPW-192736: Add check for milolibs query param

[zagi25]

Whitelist branch parameter with /^[a-zA-Z0-9_-]+$/; throw on any other characters.

Ticket

https://jira.corp.adobe.com/browse/MWPW-192736

Test URLs

Before: https://stage--bacom--adobecom.aem.page/
After: https://MWPW-192736-bacom--bacom-mwpw-192736--zagi25.aem.page/

---

This PR was generated by Claude (Anthropic's Claude Code CLI).

[aem-code-sync]

	Page	Scores	Audits	Google
📱	/		Lighthouse returned error: NOT_HTML. The page provided is not HTML (served as MIME type text/plain).
🖥️	/		Lighthouse returned error: NOT_HTML. The page provided is not HTML (served as MIME type text/plain).

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.87%. Comparing base (8d281be) to head (edc4abe).
⚠️ Report is 19 commits behind head on stage.

Additional details and impacted files

@@            Coverage Diff             @@
##            stage     #353      +/-   ##
==========================================
+ Coverage   95.82%   95.87%   +0.05%     
==========================================
  Files          13       13              
  Lines        1412     1431      +19     
==========================================
+ Hits         1353     1372      +19     
  Misses         59       59              

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