fix: dashboard metrics — real drawdown baseline, realized/unrealized split, risk radar fields

- Max drawdown was double-broken: the backend built the equity curve on a
  hardcoded $10k baseline (understating a small account's drawdown ~20x) and
  the frontend multiplied the already-percent value by 100 again (0.87% shown
  as -86.9%). The curve now starts from the trader's real initial balance
  (10k fallback when unknown) and the UI renders the percent once; the demo
  engine and type docs are aligned to percent semantics.
- Header now separates equity-based 'Total P/L (incl. unrealized)' from
  'Realized P/L (closed trades)' so it no longer contradicts profit factor /
  win rate, and the stats strip shows the fee-drag chain
  (gross - fees = net) plus a per-trade-labelled sharpe.
- Risk radar read a non-existent account field (total_unrealized_profit) so
  unrealized PnL always showed $0; small PnLs also render with cents now.
- Nav 'Connect Hyperliquid' turns into a green connected chip when the server
  already holds a fully-authorized exchange, instead of nagging forever from
  a browser without the localStorage flow state.

store/position_history.go

@@ -38,7 +38,9 @@ type HistorySummary struct {
 func (s *PositionStore) GetHistorySummary(traderID string) (*HistorySummary, error) {
 	summary := &HistorySummary{}
 
-	fullStats, err := s.GetFullStats(traderID)
+	// Baseline 0 is fine here: the summary only reads counts/win-rate/PnL, not
+	// the drawdown that depends on it.
+	fullStats, err := s.GetFullStats(traderID, 0)
 	if err != nil {
 		return nil, err
 	}