add voxel world runtime navmesh sidecar

Introduce a DI-wired NavMesh sidecar for voxel chunks so world streaming stays actor-driven and world state remains the canonical source for navigation rebuilds.

Assets/Features/VoxelWorld/Prefabs/VoxelWorld.prefab

@@ -10,6 +10,8 @@ GameObject:
   m_Component:
   - component: {fileID: 74135865886311664}
   - component: {fileID: 2927522923773808063}
+  - component: {fileID: 6182401849027620011}
+  - component: {fileID: 6182401849027620012}
   m_Layer: 0
   m_Name: VoxelWorld
   m_TagString: Untagged
@@ -47,3 +49,42 @@ MonoBehaviour:
   streamTarget: {fileID: 0}
   config: {fileID: 11400000, guid: b8cf28a5522134b479c23f017234070c, type: 2}
   _terrainShader: {fileID: 4800000, guid: ec80aebd8cb61f44cbfa6b7d5f087211, type: 3}
+--- !u!114 &6182401849027620011
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 797018065588400165}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 0c52a16bd6e44739b6bb1b4471a7a5a9, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: Assembly-CSharp::VoxelWorldScene.VoxelWorldPlayerStreamTargetBinding
+  worldGenerator: {fileID: 2927522923773808063}
+  explicitStreamTarget: {fileID: 0}
+--- !u!114 &6182401849027620012
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 797018065588400165}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 2dfd0b7ddf3a419f91ce891210f85d4b, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: Assembly-CSharp::VoxelWorldScene.VoxelWorldNavMeshLifetimeScope
+  parentReference:
+    TypeName: 
+  autoRun: 1
+  autoInjectGameObjects: []
+  enableRuntimeNavMesh: 1
+  worldGenerator: {fileID: 2927522923773808063}
+  config:
+    agentTypeId: 0
+    navRegionSizeInChunks: 2
+    maxNavMeshBuildsPerFrame: 1
+    navBoundsHorizontalPadding: 1
+    navBoundsVerticalPadding: 2
+    navWarmupRadiusInRegions: 1