Fix dashboard backtest detail, deterministic backtest seeds, paper trader fees, live node crash guard

Backtest detail: openDetail() now fetches full backtest JSON from the API
instead of showing "Full trade data not in summary". Renders equity curve
chart + full trade history table with 100 rows.

Backtest reproducibility: replaced hash(key) with fixed per-strategy seeds.
Python's hash() is randomized per process (PYTHONHASHSEED), causing wildly
different results for same strategy across runs. Now deterministic.

Server: added total_trades and sortino to /api/backtests summary response.

Paper trader: fixed Avellaneda-Stoikov simulate using TAKER_FEE instead of
MAKER_FEE. Lowered OBI signal threshold from 5bps to 1.5bps for flat markets.

Live node: added None-guard in get_mark_prices — Hyperliquid testnet API
sometimes returns null, crashing the node. Wrapped in try/except.

dashboard/server.py

@@ -174,9 +174,11 @@ async def list_backtests():
                         "start": data.get("start_time"),
                         "end": data.get("end_time"),
                         "sharpe": data.get("sharpe", 0),
+                        "sortino": data.get("sortino", 0),
                         "pnl_pct": data.get("pnl_pct", 0),
                         "max_dd": data.get("max_dd", 0),
                         "win_rate": data.get("win_rate", 0),
+                        "total_trades": data.get("total_trades", 0),
                     })
                 except (json.JSONDecodeError, IOError):
                     pass