config: autopilot to 4x 5x notional at 20x leverage; short floor 0.75 -> 0.4

Two independent changes bundled:
- Position sizing back to 4 positions x 5x equity notional at 20x leverage
  (20x total account notional, ~5% liquidation cushion) — aggressive book
  size by operator choice, for bigger single positions on a small account.
- Forced short-coverage signal floor lowered 0.75 -> 0.4. At 0.75, a
  long-leaning board left every bearish candidate below the bar, so no short
  ever opened and the book became a one-directional long bet. 0.4 keeps
  genuine directional signals so the book actually hedges — which matters
  more, not less, at 20x.

web/src/pages/StrategyStudioPage.tsx

@@ -1392,8 +1392,8 @@ export function StrategyStudioPage() {
         btc_eth_max_leverage: 20,
         altcoin_max_leverage: 20,
         // 5× equity notional per position — 4 positions = 20x total account
-        // notional (full margin at 20x). Bigger single positions, room for
-        // a balanced long/short book.
+        // 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_margin_usage: 1.0,