feat: update nav to match standard rstack-header style

- Nav changed from sticky to fixed position
- Background/border colors matched to rstack-header dark theme
- Added gradient r* logo badge (28x28, matching rstack-header dimensions)
- Added "Try Demo" button with standard rApp styling
- Right side wrapped in nav-right for consistent layout
- Hero padding adjusted for fixed nav offset
- Section scroll-margin-top set for proper anchor scrolling

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

index.html

@@ -4,7 +4,7 @@
 	<meta charset="UTF-8">
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 	<link rel="icon" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><text y='.9em' font-size='90'>📦</text></svg>">
-	<title>rStack — Open-Source Community Infrastructure</title>
+	<title>(you)rStack — Open-Source Community Infrastructure</title>
 	<meta name="description" content="A complete open-source stack for community self-governance. Self-hosted tools tied together with zero-knowledge identity and data sovereignty.">
 	<style>
 		* { margin: 0; padding: 0; box-sizing: border-box; }