feat(02-01): add accessible base styling

- Set html font-size to 100% (respects browser settings)
- Set body font-size to 1rem (16px minimum)
- Add font smoothing for better readability
- Add safe-bottom class for mobile notch support
- Add touch-target utility for WCAG 44x44px minimum

src/app.css

@@ -1 +1,24 @@
 @import 'tailwindcss';
+
+/* Ensure minimum 16px base for accessibility (UX-02) */
+html {
+  font-size: 100%; /* 16px default, respects user browser settings */
+}
+
+body {
+  font-size: 1rem; /* 16px minimum */
+  line-height: 1.5;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+/* Safe area padding for mobile devices with notches */
+.safe-bottom {
+  padding-bottom: env(safe-area-inset-bottom, 0px);
+}
+
+/* Utility for adequate touch targets (44x44px minimum per WCAG) */
+.touch-target {
+  min-height: 44px;
+  min-width: 44px;
+}