style: CSS polish, light mode verification, build fixes

- Add --primary-rgb, --transition-fast, --transition-normal CSS tokens to :root
- Add --primary-rgb override in [data-theme="light"] section
- Fix TS error: remove unused devUser prop from Route elements in App.tsx (API patching via window._devUser makes props redundant)
- Fix TS error: remove unused 'api' import from DevPanel.tsx

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/hooks/useRevealQueue.js

@@ -0,0 +1,30 @@
+import { useState, useEffect } from 'react';
+const SEEN_KEY = 'tippspiel_seen_results';
+function getSeenIds() {
+    try {
+        return new Set(JSON.parse(localStorage.getItem(SEEN_KEY) || '[]'));
+    }
+    catch {
+        return new Set();
+    }
+}
+function markSeen(matchId) {
+    const seen = getSeenIds();
+    seen.add(matchId);
+    localStorage.setItem(SEEN_KEY, JSON.stringify([...seen]));
+}
+export function useRevealQueue(matches) {
+    const [queue, setQueue] = useState([]);
+    useEffect(() => {
+        const seen = getSeenIds();
+        const unseen = matches.filter(m => m.status === 'FINISHED' && m.userTip && m.userTip.points !== null && !seen.has(m.id));
+        setQueue(unseen);
+    }, [matches]);
+    function dismissCurrent() {
+        if (queue.length === 0)
+            return;
+        markSeen(queue[0].id);
+        setQueue(q => q.slice(1));
+    }
+    return { current: queue[0] || null, remaining: queue.length, dismissCurrent };
+}