Consolidate duplicate logic to reduce code smells identified by Roslyn Bridge:
- Extract FlushPendingEdits() helper from Save() and Run() methods
- Simplify ClearData() to delegate to LoadDocumentData()
- Extract ConvertParts(), ConvertStockBins(), RunPackingAlgorithm() helpers
- Move DTO classes to separate Models.cs file
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
