feat: upgrade paper trading to $100k moderate tier

Paper money has no downside — bigger capital exposes more model
behavior: position sizing, diversification, sector exposure,
correlation checks, circuit breakers, reserve pool siphoning,
and risk tier auto-adjustment all become meaningful.

- risk_tier: conservative → moderate (min_confidence 0.55)
- absolute_position_cap: $25 → $10,000
- max_open_positions: 5 → 10
- initial portfolio value: $500 → $100,000
- Updated migration 019, Helm values, and engine default

infra/migrations/019_enable_paper_trading.sql

@@ -1,9 +1,9 @@
 -- Migration 019: Enable paper trading configuration
--- Sets conservative defaults for initial paper trading deployment.
+-- Sets moderate defaults for paper trading with $100k capital.
 -- Requirements: 16.1, 5.1
 
 UPDATE trading_engine_config
 SET enabled = true,
-    risk_tier = 'conservative',
-    absolute_position_cap = 25.0,
-    max_open_positions = 5;
+    risk_tier = 'moderate',
+    absolute_position_cap = 10000.0,
+    max_open_positions = 10;