fix: trade_budget_eur + preferred_horizon saved and reloaded in Config

Backend:
- CycleConfigRequest: add trade_budget_eur, preferred_horizon_min/max fields
  (were missing — Pydantic silently dropped them, so saves never reached set_config)
- update_cycle_config: handle + persist the 3 new fields via set_config
- get_status(): read + return trade_budget_eur/preferred_horizon_min/max from DB
  (were missing — frontend always fell back to React default values on page load)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/services/auto_cycle.py

@@ -1956,9 +1956,13 @@ def get_status() -> Dict[str, Any]:
         min_score = int(get_config("min_score_threshold") or "0")
         retention_days = int(get_config("journal_retention_days") or "90")
         maturity_pct = int(get_config("maturity_threshold_pct") or "35")
+        trade_budget_eur = float(get_config("trade_budget_eur") or "5000")
+        preferred_horizon_min = int(get_config("preferred_horizon_min") or "30")
+        preferred_horizon_max = int(get_config("preferred_horizon_max") or "180")
     except Exception:
         interval_hours, enabled, sim_threshold, min_ev, min_score = 3.0, False, 0.30, 0.0, 0
         retention_days, maturity_pct = 90, 35
+        trade_budget_eur, preferred_horizon_min, preferred_horizon_max = 5000.0, 30, 180
 
     recent = get_cycle_runs(limit=1)
     last = recent[0] if recent else None
@@ -1997,6 +2001,9 @@ def get_status() -> Dict[str, Any]:
         "min_score_threshold": min_score,
         "journal_retention_days": retention_days,
         "maturity_threshold_pct": maturity_pct,
+        "trade_budget_eur": trade_budget_eur,
+        "preferred_horizon_min": preferred_horizon_min,
+        "preferred_horizon_max": preferred_horizon_max,
         "weekend_cycle_enabled": weekend_enabled,
         "weekend_cycle_times": weekend_cycle_times,
         "last_cycle": last,