feat(core): implement namespace support and routing bindings

Introduce namespace-aware routing capabilities through a new Binding
model and updates to Master/Key entities.

- Add Binding model for configuring model routes per namespace
- Add DefaultNamespace and Namespaces fields to Master and Key models
- Update auto-migration to include Binding table
- Implement Redis synchronization for binding configurations
- Propagate namespace settings during master creation and key issuance

cmd/server/main.go

@@ -92,7 +92,7 @@ func main() {
 	logger.Info("connected to postgresql successfully")
 
 	// Auto Migrate
-	if err := db.AutoMigrate(&model.Master{}, &model.Key{}, &model.Provider{}, &model.Model{}, &model.LogRecord{}); err != nil {
+	if err := db.AutoMigrate(&model.Master{}, &model.Key{}, &model.Provider{}, &model.Model{}, &model.Binding{}, &model.LogRecord{}); err != nil {
 		fatal(logger, "failed to auto migrate", "err", err)
 	}