feat(admin): add OCR training card to admin/system page
- TrainingHistory.svelte: responsive table with status badges
(green/red/animated pulse), keyed iteration, empty-state row
- OcrTrainingCard.svelte: shows available blocks/docs, disabled states
(< 5 blocks, service down), in-flight "…" state, 5s success message,
embeds TrainingHistory
- Wired into admin/system/+page.svelte via fetchTrainingInfo() in $effect
- Regenerated api.ts with OcrTrainingRun + TrainingInfoResponse types
- TRAINING_ALREADY_RUNNING error code in errors.ts + de/en/es translations
- 7 OcrTrainingCard Vitest tests
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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