feat: add paper trading capital controls — API endpoint + UI with presets, fix status/metrics to read real state, fix migration duplicates

infra/migrations/018_autonomous_trading_engine.sql

@@ -320,6 +320,7 @@ CREATE INDEX idx_notifications_event ON notifications(event_type, created_at DES
 -- ============================================================
 
 -- Insert default trading engine configuration (moderate tier defaults)
+-- Use a singleton pattern: only insert if no rows exist
 INSERT INTO trading_engine_config (
     enabled, paused, risk_tier, reserve_siphon_pct,
     polling_interval_seconds, gradual_entry_tranches,
@@ -339,7 +340,8 @@ INSERT INTO trading_engine_config (
     notification_sms_enabled, notification_email_enabled,
     notification_rate_limit_sms_per_hour, notification_rate_limit_email_per_hour,
     notification_daily_summary_time
-) VALUES (
+)
+SELECT
     FALSE, FALSE, 'moderate', 0.20,
     60, 3,
     30.0, 15,
@@ -358,8 +360,9 @@ INSERT INTO trading_engine_config (
     FALSE, FALSE,
     10, 20,
     '16:30'
-);
+WHERE NOT EXISTS (SELECT 1 FROM trading_engine_config);
 
--- Insert initial reserve pool ledger entry with zero balance
+-- Insert initial reserve pool ledger entry with zero balance (only if empty)
 INSERT INTO reserve_pool_ledger (amount, balance_after, trigger_type, notes)
-VALUES (0.0, 0.0, 'initial', 'Initial reserve pool entry');
+SELECT 0.0, 0.0, 'initial', 'Initial reserve pool entry'
+WHERE NOT EXISTS (SELECT 1 FROM reserve_pool_ledger);