feat: redesign app UI — top nav, clean dashboard, warm branding

- Replace sidebar with top navigation bar (like Airbnb/Nextdoor)
- Redesign dashboard: home cards, coming up tasks, quick action pills
- Remove widget-heavy layout (charts, stats, activity feed)
- Add landing page with hero, features, how-it-works, CTA sections
- Update auth pages with split layout
- Clean white theme with neutral grays, brand orange/teal accents
- Friendly copy across all empty states and page headers
- Add Bricolage Grotesque + Outfit fonts
- Default to light mode

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

src/components/shared/error-banner.tsx

@@ -9,10 +9,12 @@ interface ErrorBannerProps {
 
 export function ErrorBanner({ message = "Something went wrong. Please try again.", onRetry }: ErrorBannerProps) {
   return (
-    <div role="alert" aria-live="assertive" className="rounded-lg border border-destructive/50 bg-destructive/10 p-4 flex items-center gap-3">
-      <AlertTriangle className="size-5 text-destructive shrink-0" aria-hidden="true" />
+    <div role="alert" aria-live="assertive" className="rounded-2xl border border-destructive/30 bg-destructive/5 p-4 flex items-center gap-3">
+      <div className="size-9 rounded-xl bg-destructive/10 flex items-center justify-center shrink-0">
+        <AlertTriangle className="size-4 text-destructive" aria-hidden="true" />
+      </div>
       <p className="text-sm text-destructive flex-1">{message}</p>
-      {onRetry && <Button variant="outline" size="sm" onClick={onRetry}>Retry</Button>}
+      {onRetry && <Button variant="outline" size="sm" onClick={onRetry} className="rounded-lg shrink-0">Retry</Button>}
     </div>
   );
 }