Add short signal scanner + leverage trading game engine + auto-trader

- short_scanner.py: RSI/VWAP/MACD/Bollinger-based short signal detection
- leverage_game.py: Full game engine with longs/shorts/leverage/liquidations
- leverage_trader.py: Auto-trader connecting scanners to game with TP/SL/trailing stops
- Leverage Challenge game initialized: $10K, 20x max leverage, player 'case'
- systemd timer: every 15min scan + trade
- Telegram alerts on opens/closes/liquidations

projects/crypto-signals/data/leverage-game/trader_state.json

@@ -0,0 +1,4 @@
+{
+  "peak_pnl": {},
+  "last_alert": null
+}