feat(engine): rebind live fill previews to the drawing's original frame

DefaultPlateFiller runs its search in a canonical (MBR-axis-aligned)
copy of the drawing. Intermediate progress reports — the Nesting
Progress dialog, PlateView's active-parts overlay — were showing that
transient canonical orientation instead of the drawing's real one.

FillContext.OriginalDrawing carries the pre-canonicalization drawing
through the pipeline; ReportProgress rebinds reported parts to it via
CanonicalFrame.RebindToOriginal before they reach the UI. Uses a
shallow list copy rather than per-part Part.Clone() — Clone() re-derives
its target rotation from BaseDrawing.Program.Rotation + Rotation, which
would double-count the canonical drawing's baked source angle.

OpenNest.Engine/Jobs/Placement/Fillers/DefaultPlateFiller.cs

@@ -112,7 +112,7 @@ internal class DefaultPlateFiller : PlateFillerBase
                 );
         }
 
-        var best = RunFillPipeline(canonicalItem, effectiveWorkArea, progress, token);
+        var best = RunFillPipeline(canonicalItem, originalDrawing, effectiveWorkArea, progress, token);
 
         if (
             canonicalItem.Quantity > 0
@@ -125,7 +125,7 @@ internal class DefaultPlateFiller : PlateFillerBase
             );
             PhaseResults.Clear();
             AngleResults.Clear();
-            best = RunFillPipeline(canonicalItem, workArea, progress, token);
+            best = RunFillPipeline(canonicalItem, originalDrawing, workArea, progress, token);
         }
 
         if (canonicalItem.Quantity > 0 && best.Count > canonicalItem.Quantity)
@@ -333,6 +333,7 @@ internal class DefaultPlateFiller : PlateFillerBase
 
     private List<Part> RunFillPipeline(
         NestItem item,
+        Drawing originalDrawing,
         Box workArea,
         IProgress<NestProgress> progress,
         CancellationToken token
@@ -341,6 +342,7 @@ internal class DefaultPlateFiller : PlateFillerBase
         var context = new FillContext
         {
             Item = item,
+            OriginalDrawing = originalDrawing,
             WorkArea = workArea,
             Plate = Plate,
             PlateNumber = PlateNumber,
@@ -474,7 +476,7 @@ internal class DefaultPlateFiller : PlateFillerBase
                         {
                             Phase = context.WinnerPhase,
                             PlateNumber = PlateNumber,
-                            Parts = context.CurrentBest,
+                            Parts = context.ToOriginalFrame(context.CurrentBest),
                             WorkArea = context.WorkArea,
                             Description = BuildProgressSummary(),
                             IsOverallBest = true,

OpenNest.Engine/Strategies/FillContext.cs

@@ -20,6 +20,16 @@ namespace OpenNest.Engine.Strategies
         public int MaxQuantity { get; init; }
         public PartType PartType { get; set; }
 
+        /// <summary>
+        /// The pre-canonicalization drawing that <see cref="Item"/>'s canonical copy was built
+        /// from. When set, <see cref="ReportProgress"/> rebinds reported parts to this drawing
+        /// before they reach <see cref="Progress"/>, so intermediate previews (e.g. the Nesting
+        /// Progress dialog, PlateView's active-parts overlay) show the drawing's real/visible
+        /// orientation instead of the transient canonical (MBR-axis-aligned) one. Null when the
+        /// caller isn't operating in canonical frame (e.g. tests driving a strategy directly).
+        /// </summary>
+        public Drawing OriginalDrawing { get; init; }
+
         public List<Part> CurrentBest { get; set; }
 
         /// <summary>For progress reporting only; comparisons use Policy.Comparer.</summary>
@@ -57,12 +67,32 @@ namespace OpenNest.Engine.Strategies
                 {
                     Phase = ActivePhase,
                     PlateNumber = PlateNumber,
-                    Parts = isNewBest ? parts : CurrentBest,
+                    Parts = ToOriginalFrame(isNewBest ? parts : CurrentBest),
                     WorkArea = WorkArea,
                     Description = description,
                     IsOverallBest = isNewBest,
                 }
             );
         }
+
+        /// <summary>
+        /// Rebinds <paramref name="parts"/> to <see cref="OriginalDrawing"/> for outward-facing
+        /// progress reports. Uses a shallow list copy (not per-part <see cref="Part.Clone"/>) so
+        /// <see cref="CanonicalFrame.RebindToOriginal"/>'s in-place slot replacement can't corrupt
+        /// the caller's list (e.g. <see cref="CurrentBest"/>) — <c>Part.Clone()</c> re-derives its
+        /// target rotation from <c>BaseDrawing.Program.Rotation + Rotation</c>, which double-counts
+        /// the canonical drawing's baked source angle whenever it's non-zero. No-op when
+        /// <see cref="OriginalDrawing"/> isn't set. Internal so callers that build their own
+        /// <see cref="ProgressReport"/> outside <see cref="ReportProgress"/> (e.g. the fallback
+        /// report in <c>DefaultPlateFiller.RunPipelineCore</c> for strategies that don't self-report)
+        /// can apply the same rebind before reaching the UI.
+        /// </summary>
+        internal List<Part> ToOriginalFrame(List<Part> parts)
+        {
+            if (parts == null || parts.Count == 0 || OriginalDrawing == null)
+                return parts;
+
+            return CanonicalFrame.RebindToOriginal(new List<Part>(parts), OriginalDrawing);
+        }
     }
 }