refactor: switch NewRBACClaims to return value type instead of pointer

- Update `NewRBACClaims` to return struct value types to improve safety and simplify usage.
- Adjust `jwt_test.go` to align with the updated function signature.

Signed-off-by: tbxark <tbxark@outlook.com>

Author: tbxark

server/auth/jwtauth/claims.go

@@ -15,8 +15,8 @@ type RBACClaims[T authorizer.UID] struct {
 	Roles []string `json:"roles,omitempty"`
 }
 
-func NewRBACClaims[T authorizer.UID](uid T, subject string, roles []string, expiresAt time.Time) *RBACClaims[T] {
-	return &RBACClaims[T]{
+func NewRBACClaims[T authorizer.UID](uid T, subject string, roles []string, expiresAt time.Time) RBACClaims[T] {
+	return RBACClaims[T]{
 		RegisteredClaims: jwt.RegisteredClaims{
 			Subject:   subject,
 			ExpiresAt: jwt.NewNumericDate(expiresAt),

server/auth/jwtauth/jwt_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func TestJwtAuth_GenerateToken(t *testing.T) {
-	claims := *NewRBACClaims[int64](12345, "test-subject", []string{"admin", "user"}, time.Now().Add(1*time.Hour))
+	claims := NewRBACClaims[int64](12345, "test-subject", []string{"admin", "user"}, time.Now().Add(1*time.Hour))
 	jwtAuth := NewJwtAuth[RBACClaims[int64]]("secret")
 	token, err := jwtAuth.GenerateToken(context.Background(), claims)
 	if err != nil {