Integrate chunk plan caching into the runner

internal/core/workspace/manifest_test.go

@@ -42,18 +42,6 @@ func TestManifestJSONRoundTrips(t *testing.T) {
 		}
 	})
 
-	t.Run("chunk", func(t *testing.T) {
-		manifest := ChunkManifest{
-			StageManifest: populatedManifest(StageChunk, "", "generic", started, completed),
-			ChunkCount:    3,
-		}
-		var got ChunkManifest
-		roundTripManifest(t, manifest, &got)
-		if got.ChunkCount != manifest.ChunkCount || got.Stage != StageChunk {
-			t.Fatalf("round trip chunk manifest = %+v", got)
-		}
-	})
-
 	t.Run("extract", func(t *testing.T) {
 		manifest := ExtractLaneManifest{
 			StageManifest: populatedManifest(StageExtract, "spells", "dnd/spells", started, completed),