feat: add price chart to simulation and unit tests

Unit tests (13 passing):
- Kline fetching and processing
- Price drop condition triggers buy
- Stop loss and take profit risk management
- Multiple positions (buy again after sell)
- Max candles limit
- Stop interruption handling

Frontend:
- SignalChart now shows price movement even before signals
- Shows candle count even with no signals
- Chart displays buy/sell markers when signals exist
- Canvas-based chart with gradient fill

Backend:
- Simulation stores klines for chart display
- Returns klines in API response
- Simplified simulation run (no periodic saving)

src/frontend/package.json

@@ -19,5 +19,8 @@
 		"svelte-check": "^4.4.6",
 		"typescript": "^6.0.2",
 		"vite": "^8.0.7"
+	},
+	"dependencies": {
+		"chart.js": "^4.5.1"
 	}
 }