Fix a few bugs

backend/migrations/0001_init.sql

@@ -42,6 +42,7 @@ CREATE TABLE IF NOT EXISTS relay (
   blossom_enabled INTEGER NOT NULL DEFAULT 0,
   livekit_enabled INTEGER NOT NULL DEFAULT 0,
   push_enabled INTEGER NOT NULL DEFAULT 1,
+  created_at INTEGER NOT NULL,
   FOREIGN KEY (tenant_pubkey) REFERENCES tenant(pubkey)
 );
 
@@ -114,6 +115,8 @@ CREATE INDEX IF NOT EXISTS idx_activity_unbilled ON activity (tenant_pubkey, cre
 
 CREATE INDEX IF NOT EXISTS idx_relay_tenant_pubkey ON relay (tenant_pubkey);
 
+CREATE INDEX IF NOT EXISTS idx_relay_created ON relay (created_at);
+
 CREATE INDEX IF NOT EXISTS idx_invoice_tenant_created ON invoice (tenant_pubkey, created_at);
 
 -- Dunning scans a tenant's still-open invoices oldest-first to retry payment.