refactor(engine): align namespaces with directory layout under OpenNest.Engine

All 132 OpenNest.Engine source files now declare namespaces matching
their nested directories: Jobs/, Jobs/Placement/, Jobs/Adapters/,
Fill/, RectanglePacking/, CirclePacking/, and engine-root types moved
from 'OpenNest' to 'OpenNest.Engine'. RootNamespace updated accordingly.
Consumers (Api, Console, Mcp, Benchmark, Training, desktop app, tests)
gained the explicit usings the move requires; CLAUDE.md updated.

OpenNest.Engine/Jobs/Adapters/DrawingJobMapper.cs

@@ -1,7 +1,7 @@
 using System;
 using OpenNest.CNC;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs.Adapters;
 
 /// <summary>Explicit-ID input mapping and exact supported-geometry reconstruction. Never retains caller objects.</summary>
 public static class DrawingJobMapper

OpenNest.Engine/Jobs/Adapters/LegacyPlateNesterAdapter.cs

@@ -2,7 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Threading;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs.Adapters;
 
 /// <summary>
 /// A fresh private legacy plate/drawing/item graph for each call. Only returned poses cross the boundary;

OpenNest.Engine/Jobs/Adapters/NestResultMaterializer.cs

@@ -4,7 +4,7 @@ using System.Collections.ObjectModel;
 using System.Linq;
 using OpenNest.Geometry;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs.Adapters;
 
 /// <summary>A detached mutable domain nest plus explicit requirement identity (never inferred from names).</summary>
 public sealed class MaterializedNestResult

OpenNest.Engine/Jobs/CandidateProgressBridge.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>
 /// Bridges legacy <see cref="IProgress{NestProgress}"/> reporting into job progress while a candidate

OpenNest.Engine/Jobs/FixedStrategyNestingEngine.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Threading;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>
 /// Adapts one fixed IPlateNester strategy to the whole-job INestingEngine contract, so it can compete

OpenNest.Engine/Jobs/INestingEngine.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Threading;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Synchronous whole-job solver. Cancellation throws, rather than returning partial success.</summary>
 public interface INestingEngine

OpenNest.Engine/Jobs/IPlateNester.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Threading;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Places on one sheet only. Must not change stock, demand, or caller-owned domain objects.</summary>
 public interface IPlateNester

OpenNest.Engine/Jobs/NestJob.cs

@@ -2,7 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>One material/unit system's requirements. Collections are copied; all nested values are immutable.</summary>
 public sealed class NestJob

OpenNest.Engine/Jobs/NestJobCandidateComparer.cs

@@ -2,7 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Ranks independent plate trials: priority fulfillment, sheet area, placement envelope, then input order.</summary>
 public sealed class NestJobCandidateComparer

OpenNest.Engine/Jobs/NestJobOptions.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Immutable per-job options; selection never changes the legacy global registry.</summary>
 public sealed class NestJobOptions

OpenNest.Engine/Jobs/NestJobPart.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>An immutable requirement, independent of drawing names, UI state, and drawing quantity counters.</summary>
 public sealed class NestJobPart

OpenNest.Engine/Jobs/NestJobPlacementValidator.cs

@@ -4,7 +4,9 @@ using OpenNest.Converters;
 using OpenNest.Geometry;
 using OpenNest.Math;
 
-namespace OpenNest;
+using OpenNest.Engine.Jobs.Adapters;
+using OpenNest.Engine.Jobs.Placement;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Validates a trial against immutable job geometry before the runner commits accounting.</summary>
 internal static class NestJobPlacementValidator

OpenNest.Engine/Jobs/NestJobProgress.cs

@@ -1,4 +1,4 @@
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 public enum NestJobStage
 {

OpenNest.Engine/Jobs/NestJobResult.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 public enum NestJobStatus
 {

OpenNest.Engine/Jobs/NestJobRunner.cs

@@ -3,7 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>
 /// Physical-sheet allocation. Every available stock entry is tried independently and only the selected

OpenNest.Engine/Jobs/NestJobValidator.cs

@@ -2,7 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Basic input and candidate accounting checks, NOT a geometry/clearance safety gate.</summary>
 public static class NestJobValidator

OpenNest.Engine/Jobs/NestPlateStock.cs

@@ -1,7 +1,7 @@
 using System;
 using OpenNest.Geometry;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Immutable stock settings. Size and spacing are copied value types, not caller-owned settings.</summary>
 public sealed class NestPlateStock

OpenNest.Engine/Jobs/NestingEngineInfo.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Display metadata plus a fresh-instance factory for one registered whole-job engine.</summary>
 public class NestingEngineInfo

OpenNest.Engine/Jobs/NestingEngineRegistry.cs

@@ -5,7 +5,7 @@ using System.IO;
 using System.Linq;
 using System.Reflection;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>
 /// Registry of whole-job INestingEngine implementations, parallel to NestEngineRegistry (which is for

OpenNest.Engine/Jobs/PartGeometrySnapshot.cs

@@ -3,7 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using OpenNest.CNC;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Exact immutable CNC motion values. Rapid moves retain contour/hole boundaries; arcs are not tessellated.</summary>
 public sealed record PartGeometryMotion(

OpenNest.Engine/Jobs/Placement/DefaultPlateNester.cs

@@ -3,7 +3,8 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 
-namespace OpenNest;
+using OpenNest.Engine.Jobs.Adapters;
+namespace OpenNest.Engine.Jobs.Placement;
 
 /// <summary>
 /// Migrated built-in placement strategy for the whole-job runner. Reuses <see cref="DefaultNestEngine"/>

OpenNest.Engine/Jobs/Placement/OrderedPlateNester.cs

@@ -5,7 +5,8 @@ using System.Threading;
 using OpenNest.Engine.Fill;
 using OpenNest.Geometry;
 
-namespace OpenNest;
+using OpenNest.Engine.Jobs.Adapters;
+namespace OpenNest.Engine.Jobs.Placement;
 
 /// <summary>Constrained-order linear fills in conservative rectangular free regions.
 /// Regions are only search hints; every accepted pose passes the job geometry validator.</summary>

OpenNest.Engine/Jobs/Placement/StripPlateNester.cs

@@ -2,7 +2,8 @@ using System;
 using System.Collections.Generic;
 using System.Threading;
 
-namespace OpenNest;
+using OpenNest.Engine.Jobs.Adapters;
+namespace OpenNest.Engine.Jobs.Placement;
 
 /// <summary>
 /// Migrated built-in placement strategy for the whole-job runner. Reuses <see cref="StripNestEngine"/>

OpenNest.Engine/Jobs/PlateCandidate.cs

@@ -1,6 +1,6 @@
 using System.Collections.Generic;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Owned candidate poses only; not committed fulfillment or inventory accounting.</summary>
 public sealed class PlateCandidate

OpenNest.Engine/Jobs/PlateNesterFactory.cs

@@ -1,6 +1,8 @@
 using System;
 
-namespace OpenNest;
+using OpenNest.Engine.Jobs.Adapters;
+using OpenNest.Engine.Jobs.Placement;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>
 /// Instance-scoped strategy resolution for the whole-job runner. Default and Strip resolve to the

OpenNest.Engine/Jobs/PlatePlacementRequest.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>Read-only stock settings and remaining requirements for a single candidate trial.</summary>
 public sealed class PlatePlacementRequest

OpenNest.Engine/Jobs/RotationPolicy.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace OpenNest;
+namespace OpenNest.Engine.Jobs;
 
 public enum RotationPolicyKind
 {

OpenNest.Engine/Jobs/StockLadderNestingEngine.cs

@@ -3,7 +3,9 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 
-namespace OpenNest;
+using OpenNest.Engine.Jobs.Adapters;
+using OpenNest.Engine.Jobs.Placement;
+namespace OpenNest.Engine.Jobs;
 
 /// <summary>
 /// Caller-stock-only allocation followed by bounded adjacent-sheet repacking. All replacements