brand: add (you)rStack branding to nav header

Shows [rS] badge + "(you)rStack" where "(you)" is subtly dimmed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

index.html

@@ -1035,7 +1035,7 @@
 			<div class="nav-left">
 				<a href="/" class="nav-brand">
 					<span class="nav-brand-badge" style="background:#5eead4; color:#0b1120;">rS</span>
-					rStack
+					<span style="opacity:0.45; font-weight:400;">(you)</span>rStack
 				</a>
 				<div class="app-switcher" id="appSwitcher">
 					<button class="app-switcher-trigger" id="appSwitcherTrigger" aria-expanded="false" aria-haspopup="true">