Implement design system: blob background, glassmorphism, softer corners

- globals.css: add blob keyframe animation (9s ease-in-out infinite)
- layout.tsx: add fixed background layer with 24px grid pattern and two
  animated blurred blobs (primary/5 color) that drift behind all content
- Navigation.tsx: bg-background/80 + backdrop-blur-md + border-border/50
- Sidebar.tsx: same glassmorphism treatment
- card.tsx: rounded-2xl (up from rounded-lg), bg-card/80 + backdrop-blur-sm
  so the blob color bleeds subtly through card surfaces

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

src/app/layout.tsx

@@ -44,6 +44,13 @@ export default function RootLayout({ children }: React.PropsWithChildren) {
           />
         )}
 
+        {/* Living background */}
+        <div className="pointer-events-none fixed inset-0 -z-10 overflow-hidden">
+          <div className="absolute inset-0 bg-[linear-gradient(to_right,#80808010_1px,transparent_1px),linear-gradient(to_bottom,#80808010_1px,transparent_1px)] bg-[size:24px_24px]" />
+          <div className="animate-blob absolute left-[45%] top-[30%] h-[700px] w-[700px] rounded-full bg-primary/5 blur-3xl" />
+          <div className="animate-blob absolute right-[20%] top-[60%] h-[500px] w-[500px] rounded-full bg-primary/4 blur-3xl [animation-delay:3s]" />
+        </div>
+
         <BreadcrumbProvider>
           <Navigation />
           <div className="flex flex-1 flex-col pt-16 lg:flex-row">