config: stop the churn — hold for big moves, wide TP/SL, low leverage

Live decomposition of the losing streak: 23% win rate with avg win +$1.23 /
avg loss -$1.04 on ~0.3-0.5% price moves, where the ~0.14% round-trip fee ate
30-50% of every tiny winner. Death by small-move grinding. The AI was closing
positions on ±0.5% noise after the 60m min-hold, capping winners at ~0.86%.

Redesign to 'few big positions, held for big moves':
- Throttle: min hold 60m->4h, noise-close window 90m->8h, reentry 30m->3h,
  opens/hour 30->3, opens/cycle 6->2. Noise band widened -1%..+2% -> -4%..+6%
  so small moves can no longer trigger a close.
- Exits: stop bypass -2.5% -> -5%, take-profit bypass +5% -> +12% (wide,
  asymmetric — let winners run, cut losers only on a real move).
- Leverage 20x -> 5x: a -5% stop at 20x is instant liquidation; at 5x it is
  -25% of margin, survivable. 2 positions x 2.5x = 5x total (full margin,
  ~20% cushion) instead of 4x5x=20x.
- Prompt now instructs the AI to set wide stops (~-5%) and distant targets
  (~+10-12%), hold multi-hour, and never scalp 0.5% moves.

Live strategy updated (maxPos=2, lev=5, ratio=2.5).

web/src/pages/StrategyStudioPage.tsx

@@ -1388,14 +1388,13 @@ export function StrategyStudioPage() {
       }),
       risk_control: defaultRisk({
         ...base.ai_config?.risk_control,
-        max_positions: 4,
-        btc_eth_max_leverage: 20,
-        altcoin_max_leverage: 20,
-        // 5× equity notional per position — 4 positions = 20x total account
-        // notional (full margin, ~5% liquidation cushion). Aggressive by
-        // operator choice; the 0.4 short-signal floor keeps the book balanced.
-        btc_eth_max_position_value_ratio: 5,
-        altcoin_max_position_value_ratio: 5,
+        max_positions: 2,
+        btc_eth_max_leverage: 5,
+        altcoin_max_leverage: 5,
+        // Few, concentrated positions held for big moves. 5x leverage so a
+        // wide (-5%) stop is survivable; 2 positions × 2.5x = 5x total.
+        btc_eth_max_position_value_ratio: 2.5,
+        altcoin_max_position_value_ratio: 2.5,
         max_margin_usage: 1.0,
         min_confidence: 78,
         min_risk_reward_ratio: 3,