- Add workDate field to ProgrammerTaskWorkLog (defaults to Manila day of createdAt)
- Add deltaJsonToPlainText function to quill_field.dart for Delta/plain text conversion
- Implement buildDayRows function to generate day sheet rows with proper sorting
- Implement DaySheetRow serialization and deserialization
- Add comprehensive tests for day rows builder and workDate field
- Verify backward compatibility via existing programmer_task_ledger_test
Co-Authored-By: claude-flow <ruv@ruv.net>