feat: AI-powered login page with daily greeting and animated blob background

- Add public /api/greeting endpoint that generates a daily AI greeting (cached per day)
- Replace static hero text with dynamic AI greeting (ChatGPT/Claude style)
- Add Stripe-style animated gradient blobs with 14 daily-rotating color palettes
- Use Plus Jakarta Sans font and Sparkles icon for modern AI look
- Update subtitle to "Driven by multiple AI agents"

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

apps/Frontend/src/index.css

@@ -65,6 +65,43 @@
     @apply font-sans antialiased bg-background text-foreground;
   }
 }
+@keyframes blob-float {
+  0%, 100% {
+    transform: translate(0, 0) scale(1);
+    border-radius: 40% 60% 70% 30% / 40% 50% 60% 50%;
+  }
+  25% {
+    transform: translate(80px, -60px) scale(1.25);
+    border-radius: 60% 40% 30% 70% / 60% 30% 70% 40%;
+  }
+  50% {
+    transform: translate(-50px, 50px) scale(0.85);
+    border-radius: 30% 60% 40% 70% / 50% 60% 30% 60%;
+  }
+  75% {
+    transform: translate(40px, 30px) scale(1.1);
+    border-radius: 50% 40% 60% 30% / 40% 70% 50% 60%;
+  }
+}
+
+@keyframes blob-rotate {
+  0% { transform: rotate(0deg); }
+  100% { transform: rotate(360deg); }
+}
+
+.login-blob {
+  animation: blob-float 25s ease-in-out infinite;
+}
+.login-blob-container {
+  animation: blob-rotate 50s linear infinite;
+}
+.animation-delay-2000 {
+  animation-delay: 5s;
+}
+.animation-delay-4000 {
+  animation-delay: 10s;
+}
+
 .day-picker-small-scale select {
   @apply text-sm text-gray-900 bg-white border border-gray-300 rounded-md focus:outline-none focus:border-blue-600 focus:ring-1 focus:ring-blue-600;
   height: 32px;           /* Fixed height: ~h-8 */