[kfstorm]

Summary

• Report Scene, Batch, and Line snapshots from PySubtrans's existing events. Use native translation_complete when available, with an equivalent fallback for the pinned 1.6.0 dependency.
• Keep progress in attempt-scoped memory and expose it through the Jobs list and detail APIs. Clear it on termination or deletion and initialize it again on retry.
• Show a line-based progress bar and all three counts using the existing 2-second polling. Line counts follow GUI-Subtrans 1.6.0: original lines with a translation count even in partial or errored batches; Scene and Batch counts indicate successful completion.
• Keep callbacks optional, support existing translators, and isolate observer failures from translation and checkpoint saving.

Verification

• Backend: 458 tests passed; frontend: 191 tests passed.
• Backend and frontend static checks and production Web build passed.
• Agent Browser: 402 rendered layout checks passed, plus desktop/mobile and intermediate-width visual checks in light and dark themes. Accessibility audits reported no WCAG A/AA violations.
• Repository duplication check: 0 clones.