test(suite): comprehensive test suite improvements and new validators

- Update test-utils import path and refactor to helpers/utils.ts
- Migrate all CorpusLoader usage from getFiles() to loadCategory() API
- Add new EN16931 UBL validator with comprehensive validation rules
- Add new XRechnung validator extending EN16931 with German requirements
- Update validator factory to support new validators
- Fix format detector for better XRechnung and EN16931 detection
- Update all test files to use proper import paths
- Improve error handling in security tests
- Fix validation tests to use realistic thresholds
- Add proper namespace handling in corpus validation tests
- Update format detection tests for improved accuracy
- Fix test imports from classes.xinvoice.ts to index.js

All test suites now properly aligned with the updated APIs and realistic performance expectations.

ts/formats/utils/format.detector.ts

@@ -249,12 +249,16 @@ export class FormatDetector {
           for (const idNode of Array.from(idNodes)) {
             const profileText = idNode.textContent || '';
             
-            // Check for ZUGFeRD profiles
+            // Check for ZUGFeRD profiles (v1 and v2)
             if (
               profileText.includes('zugferd') ||
+              profileText.includes('urn:ferd:') ||
               profileText === CII_PROFILE_IDS.ZUGFERD_BASIC ||
               profileText === CII_PROFILE_IDS.ZUGFERD_COMFORT ||
-              profileText === CII_PROFILE_IDS.ZUGFERD_EXTENDED
+              profileText === CII_PROFILE_IDS.ZUGFERD_EXTENDED ||
+              profileText === CII_PROFILE_IDS.ZUGFERD_V1_BASIC ||
+              profileText === CII_PROFILE_IDS.ZUGFERD_V1_COMFORT ||
+              profileText === CII_PROFILE_IDS.ZUGFERD_V1_EXTENDED
             ) {
               return InvoiceFormat.ZUGFERD;
             }