feat: add composite database indexes for query optimization

client/supabase/migrations/20260328_add_indexes.sql

@@ -0,0 +1,26 @@
+-- subscriptions table
+-- Used by: all subscription list endpoints, reminder engine, risk recalculation
+CREATE INDEX IF NOT EXISTS idx_subscriptions_user_status ON subscriptions(user_id, status);
+
+-- Used by: reminder engine to find upcoming renewals
+CREATE INDEX IF NOT EXISTS idx_subscriptions_next_renewal ON subscriptions(next_renewal_date) 
+WHERE status = 'active';
+
+-- Used by: auto-expiry service
+CREATE INDEX IF NOT EXISTS idx_subscriptions_user_billing ON subscriptions(user_id, billing_cycle);
+
+-- reminder_schedules table
+-- Used by: daily cron job to find due reminders
+CREATE INDEX IF NOT EXISTS idx_reminder_schedules_date_status ON reminder_schedules(reminder_date, status);
+
+-- Used by: deleteSubscription cleanup
+CREATE INDEX IF NOT EXISTS idx_reminder_schedules_subscription ON reminder_schedules(subscription_id);
+
+-- blockchain_logs table
+-- Used by: getAgentActivity() admin query
+CREATE INDEX IF NOT EXISTS idx_blockchain_logs_created_at ON blockchain_logs(created_at DESC);
+CREATE INDEX IF NOT EXISTS idx_blockchain_logs_subscription ON blockchain_logs(subscription_id);
+
+-- idempotency_keys table
+-- Used by: cleanupExpired() and lookup by request hash
+CREATE INDEX IF NOT EXISTS idx_idempotency_keys_expires_at ON idempotency_keys(expires_at);