test(tools): add unit tests for error handling functions

* Implement tests for error functions like errRequiredField, errInvalidField, and errEntityNotFound.
* Ensure proper metadata is returned for various error scenarios.
* Validate error handling in CRM, Files, and other tools.
* Introduce tests for parsing stored file IDs and UUIDs.
* Enhance coverage for helper functions related to project resolution and session management.

internal/auth/oauth_registry_test.go

@@ -60,7 +60,6 @@ func TestMiddlewareAllowsOAuthBasicAuthAndSetsContext(t *testing.T) {
 	}
 }
 
-
 func TestMiddlewareRejectsOAuthMissingOrInvalidCredentials(t *testing.T) {
 	oauthRegistry, err := NewOAuthRegistry([]config.OAuthClient{{
 		ID:           "oauth-client",