test(chat,playout): enable test suite, coverage gate, switch to pure-Go SQLite driver

backend/chat/src/db/db.go

@@ -6,8 +6,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/glebarez/sqlite"
 	"gorm.io/driver/postgres"
-	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
 )