refactor: UX and styling improvements across frontend

- Fix login spinner (isLoading never set to true before await)
- Extract PageHero component, replace copy-pasted hero sections on videos/models/tags pages
- Replace inline plasma blobs with SexyBackground on videos/models/tags pages
- Make video/model/tag cards fully clickable (wrap in <a>), remove redundant Watch/View Profile buttons
- Convert inner overlay anchors to divs to avoid nested <a> elements
- Fix home page model avatar preset: mini → thumbnail (correct size for 96px display)
- Reduce home hero height: min-h-screen → min-h-[70vh]
- Remove dead hideName prop from Logo, simplify component
- Add brand name to mobile flyout panel header with gradient styling
- Remove dead _relatedVideos array, isBookmarked state, _handleBookmark from video detail page
- Clean up commented-out code blocks in video detail and models pages
- Note: tag card inner tag links converted to spans to avoid nested anchors

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

packages/frontend/src/lib/components/header/header.svelte

@@ -56,7 +56,7 @@
         href="/"
         class="flex w-full items-center gap-3 hover:scale-105 transition-all duration-300"
       >
-        <Logo hideName={true} />
+        <Logo />
       </a>
 
       <!-- Desktop Navigation -->
@@ -191,8 +191,13 @@
   inert={!isMobileMenuOpen || undefined}
 >
   <!-- Panel header -->
-  <div class="flex items-center px-5 h-16 shrink-0 border-b border-border/30">
-    <Logo hideName={true} />
+  <div class="flex items-center gap-3 px-5 h-16 shrink-0 border-b border-border/30">
+    <Logo />
+    <span
+      class="text-xl font-extrabold bg-gradient-to-r from-primary to-accent bg-clip-text text-transparent"
+    >
+      {$_("brand.name")}
+    </span>
   </div>
 
   <div class="flex-1 py-6 px-5 space-y-6">