Add unified FEN/PGN import with auto-detection

- Create chessFormatDetector utility for automatic format detection
- Update StartScreen with textarea supporting both FEN and PGN input
- Add real-time format detection with visual feedback indicators
- Update translations for all 4 languages (EN, DE, FR, IT)
- Add markdown rendering for Tutor chat messages
- Add comprehensive tests for format detection (20 tests)
- Update game initialization to handle both FEN and PGN formats

This completes the fix/stale-analysis-data branch with:
- Fixed stale evaluation data in hint/best move requests
- Clarified AI's dual role (opponent + tutor) to prevent hint rejection
- Stored complete evaluation history (P0, P1, P2) for all moves
- Improved end-game analysis with better mistake detection
- Fixed duplicate analysis runs with useRef flag
- Added markdown rendering for formatted analysis output
- Added unified FEN/PGN import with auto-detection

src/app/page.tsx

@@ -44,6 +44,7 @@ export default function Home() {
         personality: Personality;
         color: 'white' | 'black' | 'random';
         fen?: string;
+        pgn?: string;
     }) => {
         const color = options.color === 'random'
             ? (Math.random() < 0.5 ? 'white' : 'black')
@@ -51,6 +52,7 @@ export default function Home() {
 
         setGameProps({
             initialFen: options.fen,
+            initialPgn: options.pgn,
             initialPersonality: options.personality,
             initialColor: color
         });