Opus 5 Referral Tag Sanitization — Only Named Partners Displayed

KEYSTONE referral tag display was tightened after the junk src tag incident: only src values matching named partners (owlet, awh, groknews, aivn, dsg, fables, wellbeing, quietrooms, designgallery) are printed by name. All other src values collapse to other in the public stats table. This prevents random or malicious URL parameters from appearing on the public page.