feat: move revision tracking to ExportRecord, add perceptual hash comparison, cut list modal, and auto-start API

- Move Revision from Drawing to ExportRecord so each export captures its own revision snapshot
- Add Hamming distance comparison for perceptual hashes (tolerance of 10 bits) to avoid false revision bumps
- Replace CoenM.ImageHash with inline DifferenceHash impl (compatible with ImageSharp 3.x)
- Increase PDF render DPI from 72 to 150 for better hash fidelity
- Add download-dxfs-by-drawing endpoint for cross-export DXF zip downloads
- Prefix DXF filenames with equipment number when no drawing number is present
- Pass original filename to storage service for standalone part exports
- Auto-start FabWorks.Api from ExportDXF client if not already running
- Add cut list modal with copy-to-clipboard in the web UI
- Update PDF hash on existing export records after upload
- Bump static asset cache versions to v3

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

FabWorks.Core/Models/Drawing.cs

@@ -8,7 +8,6 @@ namespace FabWorks.Core.Models
         public string DrawingNumber { get; set; }
         public string Title { get; set; }
         public string PdfContentHash { get; set; }
-        public int Revision { get; set; } = 1;
 
         public virtual ICollection<ExportRecord> ExportRecords { get; set; } = new List<ExportRecord>();
     }

FabWorks.Core/Models/ExportRecord.cs

@@ -17,6 +17,7 @@ namespace FabWorks.Core.Models
         public string PdfContentHash { get; set; }
 
         public int? DrawingId { get; set; }
+        public int? DrawingRevision { get; set; }
         public virtual Drawing Drawing { get; set; }
 
         public virtual ICollection<BomItem> BomItems { get; set; } = new List<BomItem>();