feat: Enhance Game component with extra puzzles feature

- Introduce requiredDailyKeys to track daily puzzle completion across genres.
- Implement logic to show an ExtraPuzzlesPopover when all daily puzzles are completed.
- Add localized messages for extra puzzles in both English and German.
- Update GenrePage and Home components to pass requiredDailyKeys to the Game component.

lib/externalPuzzles.ts

@@ -0,0 +1,47 @@
+export type ExternalPuzzle = {
+    id: string;
+    nameDe: string;
+    nameEn: string;
+    url: string;
+    isActive?: boolean;
+};
+
+/**
+ * Zentrale Liste externer Rätselangebote.
+ * 
+ * Erweiterung: Einfach neuen Eintrag in dieses Array hinzufügen.
+ */
+export const externalPuzzles: ExternalPuzzle[] = [
+    {
+        id: 'pastpuzzle',
+        nameDe: 'Past Puzzle',
+        nameEn: 'Past Puzzle',
+        url: 'https://www.pastpuzzle.de/#/',
+        isActive: true,
+    },
+    {
+        id: 'woerdle',
+        nameDe: 'Wördle',
+        nameEn: 'Wördle',
+        url: 'https://www.wördle.de',
+        isActive: true,
+    },
+    {
+        id: 'ciddle',
+        nameDe: 'Ciddle',
+        nameEn: 'Ciddle',
+        url: 'https://ciddle.winklerweb.net',
+        isActive: true,
+    },
+];
+
+export function getRandomExternalPuzzle(): ExternalPuzzle | null {
+    const activePuzzles = externalPuzzles.filter(p => p.isActive !== false);
+    if (activePuzzles.length === 0) {
+        return null;
+    }
+    const index = Math.floor(Math.random() * activePuzzles.length);
+    return activePuzzles[index] ?? null;
+}
+
+