Add separate EquipmentNo and DrawingNo fields alongside the combined
DrawingNumber, plus a Title field for labeling exports. Updated across
Core model, DbContext, API DTOs, and ExportDXF models.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add FileStorageService for DXF/PDF storage using content hashing,
FileStorageOptions config, FilesController for uploads, and
FileBrowserController for browsing stored files.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
