Add find-existing endpoint and upsert logic to POST so re-exporting
a part updates the existing BomItem rather than creating duplicates.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add list/search, equipment/drawing number lookups, PDF hash tracking,
cut template lookup, DXF zip download, and wire up FileStorageService
and static files in Program.cs.
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>
