feat(auth): add authenticate callback for fallback logic

* Implement SetAuthenticateCallback in authenticators
* Update Authenticate methods to use callback on failure

pkg/security/provider_test.go

@@ -38,6 +38,8 @@ func (m *mockSecurityProvider) Authenticate(r *http.Request) (*UserContext, erro
 	return m.authUser, m.authError
 }
 
+func (m *mockSecurityProvider) SetAuthenticateCallback(_ func(r *http.Request) (*UserContext, error)) {}
+
 func (m *mockSecurityProvider) GetColumnSecurity(ctx context.Context, userID int, schema, table string) ([]ColumnSecurity, error) {
 	return m.columnSecurity, nil
 }