OcrTrainingService.triggerTraining() and triggerSegTraining() held a DB
connection open for the entire ketos training run (potentially minutes),
risking connection pool exhaustion. Replaced class-level @Transactional
with TransactionTemplate for narrow DB writes: guard+create and
result-record each run in their own short transaction; the HTTP call to
the OCR service runs between them with no open connection.
Also replaces blockRepository.findAll().size() with blockRepository.count()
in getTrainingInfo() to avoid loading every block into heap on each poll.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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