refactor(auth): delegate access control to be-system

Remove Agent Desk users, roles, login sessions, tokens, and local permission persistence. Expose the backend as an embeddable ai-agent module with host-provided subject lookup and operation authorization callbacks, and complete the frontend/backend repository split.

cmd/generator/generator.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"agent-desk/internal/models"
+	"code.tczkiot.com/wlw/ai-agent/internal/models"
 
 	"github.com/mlogclub/codegen"
 )
@@ -19,19 +19,10 @@ func main() {
 			WebEdit:    false,
 		},
 		codegen.GetGenerateStruct(&models.Migration{}),
-		codegen.GetGenerateStruct(&models.User{}),
-		codegen.GetGenerateStruct(&models.UserIdentity{}),
 		codegen.GetGenerateStruct(&models.Company{}),
 		codegen.GetGenerateStruct(&models.Customer{}),
 		codegen.GetGenerateStruct(&models.CustomerIdentity{}),
 		codegen.GetGenerateStruct(&models.CustomerContact{}),
-		codegen.GetGenerateStruct(&models.Role{}),
-		codegen.GetGenerateStruct(&models.Permission{}),
-		codegen.GetGenerateStruct(&models.UserRole{}),
-		codegen.GetGenerateStruct(&models.RolePermission{}),
-		codegen.GetGenerateStruct(&models.UserPermission{}),
-		codegen.GetGenerateStruct(&models.LoginSession{}),
-		codegen.GetGenerateStruct(&models.LoginCredentialLog{}),
 		codegen.GetGenerateStruct(&models.Asset{}),
 		codegen.GetGenerateStruct(&models.Tag{}),
 		codegen.GetGenerateStruct(&models.Conversation{}),