feat(questions): add questions page with open count badge

Add /questions page and a nav badge with the open count.
Core decides which question is open. The page only shows and answers.
Move RatingStars out of BacklogCard so both pages share it.

src/components/RatingStars.jsx

@@ -0,0 +1,32 @@
+import {useTranslation} from 'react-i18next';
+import {Star} from 'lucide-react';
+
+import {cn} from '@/lib/utils';
+
+/**
+ * Five star buttons. Clicking the chosen star again sends 0, so the parent decides what that means.
+ *
+ * @param value 0 for no rating
+ * @param labelledBy id of the element that names the group
+ */
+export default function RatingStars({value, onChange, labelledBy, disabled}) {
+    const {t} = useTranslation();
+    return (
+        <div role="group" aria-labelledby={labelledBy} className="flex h-9 items-center gap-1">
+            {[1, 2, 3, 4, 5].map((n) => (
+                <button
+                    key={n}
+                    type="button"
+                    disabled={disabled}
+                    aria-label={t('BACKLOG.RATING_STARS', {count: n})}
+                    aria-pressed={value === n}
+                    onClick={() => onChange(value === n ? 0 : n)}
+                    className="rounded-sm p-0.5 outline-none focus-visible:ring-[3px] focus-visible:ring-ring/50"
+                >
+                    <Star className={cn('size-6 transition-colors',
+                        n <= value ? 'fill-amber-400 text-amber-400' : 'text-muted-foreground/40 hover:text-amber-400')}/>
+                </button>
+            ))}
+        </div>
+    );
+}