feat: add PDF report generation for backtest executions

- Implemented `generate_backtest_report` to create PDF reports for backtest results.
- Added `report_file` field to `StrategyExecution` for storing report paths.
- Introduced `/executions/<execution_id>/report/` endpoint for downloading reports.
- Enhanced backtesting flow to generate and save reports upon completion.
- Updated dependencies to include `matplotlib` for report generation.

strategies/services/report.py

@@ -0,0 +1,158 @@
+import logging
+import os
+
+import matplotlib
+matplotlib.use('Agg')
+import matplotlib.pyplot as plt
+from matplotlib.backends.backend_pdf import PdfPages
+
+from django.conf import settings
+
+logger = logging.getLogger(__name__)
+
+
+def generate_backtest_report(result, execution_id):
+    """백테스트 결과를 PDF 리포트로 생성
+
+    Args:
+        result: run_backtest()가 반환한 결과 딕셔너리
+        execution_id: StrategyExecution ID
+
+    Returns:
+        MEDIA_ROOT 기준 상대 경로 (예: 'reports/backtest_1.pdf')
+    """
+    reports_dir = os.path.join(settings.MEDIA_ROOT, 'reports')
+    os.makedirs(reports_dir, exist_ok=True)
+
+    relative_path = f'reports/backtest_{execution_id}.pdf'
+    file_path = os.path.join(settings.MEDIA_ROOT, relative_path)
+
+    with PdfPages(file_path) as pdf:
+        _draw_summary_page(pdf, result)
+        _draw_equity_curve_page(pdf, result)
+
+    logger.info(f'PDF report generated: {file_path}')
+    return relative_path
+
+
+def _draw_summary_page(pdf, result):
+    """페이지 1: 입력 파라미터 + 성과 지표"""
+    fig, (ax_params, ax_metrics) = plt.subplots(2, 1, figsize=(8.27, 11.69))
+    fig.suptitle(f"Backtest Report: {result.get('strategy', 'N/A')}", fontsize=16, fontweight='bold', y=0.97)
+
+    # 입력 파라미터 테이블
+    ax_params.set_title('Input Parameters', fontsize=13, fontweight='bold', loc='left', pad=12)
+    ax_params.axis('off')
+
+    variant = result.get('variant', '')
+    param_data = [
+        ['Strategy', result.get('strategy', 'N/A')],
+        ['Variant', variant if variant else 'N/A'],
+        ['Period', f"{result.get('backtest_start_date', '')} ~ {result.get('backtest_end_date', '')}"],
+        ['Initial Capital', f"${result.get('initial_capital', 0):,.0f}"],
+        ['Final Capital', f"${result.get('final_capital', 0):,.0f}"],
+    ]
+
+    param_table = ax_params.table(
+        cellText=param_data,
+        colLabels=['Parameter', 'Value'],
+        colWidths=[0.35, 0.55],
+        loc='center',
+        cellLoc='left',
+    )
+    param_table.auto_set_font_size(False)
+    param_table.set_fontsize(10)
+    param_table.scale(1, 1.6)
+    for (row, col), cell in param_table.get_celld().items():
+        if row == 0:
+            cell.set_facecolor('#4472C4')
+            cell.set_text_props(color='white', fontweight='bold')
+        else:
+            cell.set_facecolor('#F2F2F2' if row % 2 == 0 else 'white')
+
+    # 성과 지표 테이블
+    ax_metrics.set_title('Performance Metrics', fontsize=13, fontweight='bold', loc='left', pad=12)
+    ax_metrics.axis('off')
+
+    metrics = result.get('metrics', {})
+    metrics_data = [
+        ['CAGR', f"{metrics.get('cagr', 0):.2f}%"],
+        ['Total Return', f"{metrics.get('total_return', 0):.2f}%"],
+        ['Annual Volatility', f"{metrics.get('annual_volatility', 0):.2f}%"],
+        ['Max Drawdown', f"{metrics.get('max_drawdown', 0):.2f}%"],
+        ['Sharpe Ratio', f"{metrics.get('sharpe_ratio', 0):.2f}"],
+        ['Sortino Ratio', f"{metrics.get('sortino_ratio', 0):.2f}"],
+        ['Calmar Ratio', f"{metrics.get('calmar_ratio', 0):.2f}"],
+        ['Win Rate (Monthly)', f"{metrics.get('win_rate', 0):.2f}%"],
+        ['Best Month', f"{metrics.get('best_month', 0):.2f}%"],
+        ['Worst Month', f"{metrics.get('worst_month', 0):.2f}%"],
+    ]
+
+    metrics_table = ax_metrics.table(
+        cellText=metrics_data,
+        colLabels=['Metric', 'Value'],
+        colWidths=[0.35, 0.55],
+        loc='center',
+        cellLoc='left',
+    )
+    metrics_table.auto_set_font_size(False)
+    metrics_table.set_fontsize(10)
+    metrics_table.scale(1, 1.6)
+    for (row, col), cell in metrics_table.get_celld().items():
+        if row == 0:
+            cell.set_facecolor('#4472C4')
+            cell.set_text_props(color='white', fontweight='bold')
+        else:
+            cell.set_facecolor('#F2F2F2' if row % 2 == 0 else 'white')
+
+    fig.tight_layout(rect=[0, 0, 1, 0.95])
+    pdf.savefig(fig)
+    plt.close(fig)
+
+
+def _draw_equity_curve_page(pdf, result):
+    """페이지 2: 에쿼티 커브 차트"""
+    equity_curve = result.get('daily_equity_curve', [])
+    if not equity_curve:
+        return
+
+    dates = [entry['date'] for entry in equity_curve]
+    values = [entry['value'] for entry in equity_curve]
+
+    fig, ax = plt.subplots(figsize=(8.27, 11.69 / 2))
+    fig.suptitle('Equity Curve', fontsize=14, fontweight='bold')
+
+    ax.plot(range(len(values)), values, color='#4472C4', linewidth=1.2)
+    ax.fill_between(range(len(values)), values, alpha=0.1, color='#4472C4')
+    ax.set_ylabel('Portfolio Value ($)')
+    ax.set_xlabel('Date')
+    ax.grid(True, alpha=0.3)
+    ax.yaxis.set_major_formatter(plt.FuncFormatter(lambda x, p: f'${x:,.0f}'))
+
+    # x축 레이블: 적당한 간격으로 날짜 표시
+    num_labels = min(8, len(dates))
+    if num_labels > 0:
+        step = max(1, len(dates) // num_labels)
+        tick_positions = list(range(0, len(dates), step))
+        tick_labels = [dates[i] for i in tick_positions]
+        ax.set_xticks(tick_positions)
+        ax.set_xticklabels(tick_labels, rotation=45, ha='right', fontsize=8)
+
+    # Drawdown subplot
+    drawdown_series = result.get('drawdown_series', [])
+    if drawdown_series:
+        ax2 = fig.add_axes([0.125, 0.08, 0.775, 0.2])
+        dd_values = [d['drawdown'] for d in drawdown_series]
+        ax2.fill_between(range(len(dd_values)), dd_values, color='#C0504D', alpha=0.4)
+        ax2.plot(range(len(dd_values)), dd_values, color='#C0504D', linewidth=0.8)
+        ax2.set_ylabel('Drawdown (%)')
+        ax2.grid(True, alpha=0.3)
+        ax2.set_xlim(ax.get_xlim())
+        ax2.set_xticklabels([])
+
+        # 메인 차트 여백 조정
+        ax.set_position([0.125, 0.35, 0.775, 0.55])
+
+    fig.tight_layout(rect=[0, 0.05, 1, 0.95])
+    pdf.savefig(fig)
+    plt.close(fig)