feat: cream terminal redesign, English-only UI, autopilot launch fixes

- Redesign dashboard into a cream-paper + vermilion IBM Plex Mono terminal
  (live L2 order book, cost/liq map, WS K-line, signal matrix, orchestration
  topology, risk radar, execution log, current positions, equity curve)
- Convert all user-facing UI and backend strings/prompts from Chinese to
  English (multi-language retained, default English)
- Add /api/statistics/full endpoint + full-stats frontend wiring
- Fix Autopilot launch: reuse the existing trader instead of creating
  duplicates (eliminates repeat ~35s create cost and stale-trader 404s);
  launch sends 5m scan interval
- Fix unreadable toasts: cream theme with high-contrast text + per-type accent
- Silence background dashboard polls (getTraderConfig) to stop error-toast spam

trader/auto_trader_loop.go

@@ -222,6 +222,9 @@ func (at *AutoTrader) runCycle() error {
 	// 8. Sort decisions: ensure close positions first, then open positions (prevent position stacking overflow)
 	sortedDecisions := sortDecisionsByPriority(aiDecision.Decisions)
 	sortedDecisions = at.filterDecisionsToStrategyUniverse(sortedDecisions, ctx)
+	// Per-cycle long/short coverage: if the AI left a direction uncovered, force
+	// the strongest bullish/bearish candidate (account-sized, risk-enforced).
+	sortedDecisions = at.ensureLongShortCoverage(sortedDecisions, ctx, ctx.Account.TotalEquity)
 
 	logger.Info("🔄 Execution order (optimized): Close positions first → Open positions later")
 	for i, d := range sortedDecisions {