style(css): add smooth transition variables and prefers-reduced-motion support

src/app/globals.css

@@ -103,6 +103,11 @@
 	--navbar-height: 56px;
 	--muted: var(--color-text-muted);
 	--border-subtle: color-mix(in srgb, var(--color-text-muted) 18%, transparent);
+	/* Transition variables for smoother, consistent UI */
+	--transition-fast: 0.1s;
+	--transition-normal: 0.2s;
+	--transition-slow: 0.3s;
+	--ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
 }
 
 /* Dark mode colors + readable contrast vars are generated by ThemeVars. */
@@ -126,6 +131,20 @@ html {
 	-webkit-text-size-adjust: 100%;
 	text-size-adjust: 100%;
 }
+
+@media (prefers-reduced-motion: reduce) {
+	html:focus-within {
+		scroll-behavior: auto;
+	}
+	*,
+	*::before,
+	*::after {
+		animation-duration: 0.01ms !important;
+		animation-iteration-count: 1 !important;
+		transition-duration: 0.01ms !important;
+		scroll-behavior: auto !important;
+	}
+}
 body {
 	font-family: var(--font-family);
 	color: var(--color-text-readable, var(--color-text, #0f172a));