feat: standardize input styling with tier system, add depth and admin features

- Define 4 input tier CSS classes (input-standard, input-search, input-embedded, input-danger)
  in globals.css, migrating ~50 inputs across ~28 component files to use them
- Add subtle border and inset shadow to solid input tiers for resting-state visibility
- Fix focus ring clipping in settings panel scroll container
- Fix phantom Tailwind tokens (border-border-primary, placeholder-txt-muted)
- Add admin user management panel, storage management, and account deletion utilities

packages/web/src/components/ui/UserProfilePopout.tsx

@@ -68,7 +68,7 @@ export function UserProfilePopout({ user, onClose, position }: UserProfilePopout
 
   // Banner display
   const bannerSrc = user.banner
-    ? (user.banner.startsWith('http') ? user.banner : userApi.uploads.url(user.banner))
+    ? (user.banner.startsWith('http') || user.banner.startsWith('/') ? user.banner : userApi.uploads.url(user.banner))
     : null;
   const bannerFallback = user.accentColor
     ? mutedGradient(user.accentColor, adjustColor(user.accentColor, -40))