feat: add AppSelect custom dropdown component

src/styles/main.css

@@ -119,6 +119,22 @@
   animation: modal-enter 200ms ease-out;
 }
 
+/* Dropdown animations */
+@keyframes dropdown-enter {
+  from {
+    opacity: 0;
+    transform: translateY(-4px) scale(0.98);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0) scale(1);
+  }
+}
+
+.animate-dropdown-enter {
+  animation: dropdown-enter 150ms ease-out;
+}
+
 /* Toast animations */
 @keyframes toast-enter {
   from {