Kraken 7 removed support for the legacy `path` format (image + .gt.txt
pairs) in VGSLRecognitionDataModule despite the CLI still advertising it.
Switching to PAGE XML (-f page) format which is the supported standard.
- Java export now writes .xml alongside .png (PAGE XML with TextLine,
Baseline at 75% height, and Unicode transcription)
- XML special characters in transcription text are escaped (& < >)
- Python trainer globs *.xml and passes -f page to ketos train
- Regenerated frontend API types to include cer/loss/accuracy/epochs on
OcrTrainingRun (were missing, causing empty CER column in history)
- Updated and extended TrainingDataExportServiceTest
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>