Add fleet stats table with funds, fees, loss streak, and totals.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_stats_summary_extra.py

@@ -0,0 +1,28 @@
+"""统计汇总：最大单笔亏损、连亏次数。"""
+
+from __future__ import annotations
+
+from app.api.stats import _current_loss_streak
+
+
+def test_current_loss_streak() -> None:
+    assert _current_loss_streak([]) == 0
+    assert (
+        _current_loss_streak(
+            [
+                {"realized_pnl": 10},
+                {"realized_pnl": -1},
+                {"realized_pnl": -2},
+            ]
+        )
+        == 2
+    )
+    assert (
+        _current_loss_streak(
+            [
+                {"realized_pnl": -5},
+                {"realized_pnl": 1},
+            ]
+        )
+        == 0
+    )