refactor: update Conversation model to include CustomerName, adjust related logic and queries

internal/migration/000006_backfill_conversation_customer_name.go

@@ -0,0 +1,24 @@
+package migration
+
+import (
+	"cs-agent/internal/models"
+
+	"github.com/mlogclub/simple/sqls"
+)
+
+func init() {
+	register(6, "backfill conversation customer name", func() error {
+		db := sqls.DB()
+		if !db.Migrator().HasColumn(&models.Conversation{}, "customer_name") {
+			return nil
+		}
+		return db.Exec(`
+UPDATE t_conversation
+SET customer_name = (
+  SELECT name FROM t_customer WHERE t_customer.id = t_conversation.customer_id
+)
+WHERE customer_id > 0
+  AND (customer_name = '' OR customer_name IS NULL)
+`).Error
+	})
+}