fix(uix): RadioCards — hover on a selected card keeps the active colour

The hover rule out-specified the checked rule, so hovering a selected card
reverted it to the neutral (unselected) hover colour — visually undoing the
selection. Now the neutral hover excludes `[data-state='checked']`, and a
dedicated checked-hover rule keeps the active colour and just deepens it a
notch (border → --_radio-group-palette-solid-hover, tint 7% → 12%). Selection
state is never affected by hover.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/uix/eidos/components/radio-cards/radio-cards.css

@@ -81,11 +81,23 @@
 
 /* ── Hover / focus ──────────────────────────────────────────────────────── */
 
-[data-radio-cards] [data-radio-cards-item]:hover:not([data-disabled]):not([data-readonly]) {
+/* Hover — UNCHECKED card only: neutral lift. Excludes checked so hovering a
+ * selected card never reverts it to the unselected hover colour. */
+[data-radio-cards]
+	[data-radio-cards-item]:hover:not([data-disabled]):not([data-readonly]):not([data-state='checked']) {
 	border-color: var(--radio-cards-border-hover);
 	background: var(--radio-cards-bg-hover);
 }
 
+/* Hover — SELECTED card: stay in the active colour, just deepen a notch
+ * (darker tone via the palette hover token + a slightly more opaque tint).
+ * Selection state is unaffected by hover. */
+[data-radio-cards]
+	[data-radio-cards-item][data-state='checked']:hover:not([data-disabled]):not([data-readonly]) {
+	border-color: var(--_radio-group-palette-solid-hover);
+	background: color-mix(in srgb, var(--_radio-group-palette-solid) 12%, var(--color-surface-default));
+}
+
 [data-radio-cards] [data-radio-cards-item]:focus-visible {
 	box-shadow: var(--radio-cards-focus-ring);
 }