Accessibility overhaul

frontend/src/utils/a11y.ts

@@ -0,0 +1,9 @@
+import type { KeyboardEvent } from 'react';
+
+/** Activate a clickable non-button element on Enter or Space, mirroring native button behavior. */
+export function handleKeyboardActivate(e: KeyboardEvent) {
+  if (e.key === 'Enter' || e.key === ' ') {
+    e.preventDefault();
+    (e.currentTarget as HTMLElement).click();
+  }
+}