feat: enhance backtest with real-time positions, P&L fixes, and strategy integration

- Add real-time position display with unrealized P&L during backtest
- Fix P&L calculation by tracking accumulated opening fees
- Add strategy coin source resolution (AI500, OI Top, mixed)
- Infer AI provider from model name for better compatibility
- Cap position size to available margin to prevent insufficient cash errors
- Fix trade markers on K-line chart (long/short instead of buy/sell)
- Add QuantData and OI ranking to backtest decision context

web/src/lib/api.ts

@@ -20,6 +20,7 @@ import type {
   BacktestTradeEvent,
   BacktestMetrics,
   BacktestRunMetadata,
+  BacktestKlinesResponse,
   Strategy,
   StrategyConfig,
   DebateSession,
@@ -580,6 +581,19 @@ export const api = {
     return handleJSONResponse<BacktestMetrics>(res)
   },
 
+  async getBacktestKlines(
+    runId: string,
+    symbol: string,
+    timeframe?: string
+  ): Promise<BacktestKlinesResponse> {
+    const query = new URLSearchParams({ run_id: runId, symbol })
+    if (timeframe) query.set('timeframe', timeframe)
+    const res = await fetch(`${API_BASE}/backtest/klines?${query}`, {
+      headers: getAuthHeaders(),
+    })
+    return handleJSONResponse<BacktestKlinesResponse>(res)
+  },
+
   async getBacktestTrace(
     runId: string,
     cycle?: number