feat: save element tool selection

Memola/Canvas/Tool/Core/Tool.swift

@@ -31,10 +31,15 @@ public class Tool: NSObject, ObservableObject {
 
     init(object: ToolObject) {
         self.object = object
+        selection = ToolSelection(rawValue: object.selection) ?? .hand
     }
 
     func selectTool(_ selection: ToolSelection) {
         self.selection = selection
+        withPersistence(\.viewContext) { [weak object] context in
+            object?.selection = selection.rawValue
+            try context.saveIfNeeded()
+        }
     }
 
     func load() {

Memola/Canvas/Tool/Core/ToolSelection.swift

@@ -7,7 +7,7 @@
 
 import Foundation
 
-enum ToolSelection: Equatable {
+enum ToolSelection: Int16, Equatable {
     case hand
     case pen
     case photo

Memola/Features/Memos/MemosView.swift

@@ -73,6 +73,7 @@ struct MemosView: View {
         canvasObject.height = 8_000
 
         let toolObject = ToolObject(\.viewContext)
+        toolObject.selection = 0
         toolObject.pens = []
 
         let eraserPenObject = PenObject.createObject(\.viewContext, penStyle: .eraser)

Memola/Persistence/Objects/ToolObject.swift

@@ -10,6 +10,7 @@ import Foundation
 
 @objc(ToolObject)
 class ToolObject: NSManagedObject {
+    @NSManaged var selection: Int16
     @NSManaged var pens: NSMutableSet
     @NSManaged var memo: MemoObject?
 }

Memola/Resources/Models/MemolaModel.xcdatamodeld/MemolaModel.xcdatamodel/contents

@@ -73,6 +73,7 @@
         <relationship name="quads" toMany="YES" deletionRule="Cascade" ordered="YES" destinationEntity="QuadObject" inverseName="stroke" inverseEntity="QuadObject"/>
     </entity>
     <entity name="ToolObject" representedClassName="ToolObject" syncable="YES">
+        <attribute name="selection" attributeType="Integer 16" defaultValueString="0" usesScalarValueType="YES"/>
         <relationship name="memo" optional="YES" maxCount="1" deletionRule="Nullify" destinationEntity="MemoObject" inverseName="tool" inverseEntity="MemoObject"/>
         <relationship name="pens" toMany="YES" deletionRule="Cascade" destinationEntity="PenObject" inverseName="tool" inverseEntity="PenObject"/>
     </entity>