fix: GPU-accelerate blob animations to prevent layout jitter

Added will-change:transform, contain:layout style, and
backface-visibility:hidden to all blob animations. This promotes
blobs to their own GPU compositing layer, preventing them from
triggering main-thread reflow/repaint that causes page shaking.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/index.css

@@ -125,6 +125,13 @@
   }
 }
 
+/* GPU-accelerate all blob animations to prevent layout jitter */
+.animate-blob, .animate-blob-large {
+  will-change: transform;
+  contain: layout style;
+  backface-visibility: hidden;
+}
+
 .animate-blob-large {
   animation: blob-large 25s infinite ease-in-out;
 }