refactor: switch CustomizeZapView to use a model

Changelog-Fixed: Fix CustomizeZapView from randomly disappearing

damus/Models/Zaps/CustomizeZapModel.swift

@@ -0,0 +1,30 @@
+//
+//  CustomizeZapModel.swift
+//  damus
+//
+//  Created by William Casarin on 2023-06-22.
+//
+
+import Foundation
+
+
+class CustomizeZapModel: ObservableObject {
+    @Published var comment: String = ""
+    @Published var custom_amount: String = ""
+    @Published var custom_amount_sats: Int? = nil
+    @Published var zap_type: ZapType = .pub
+    @Published var invoice: String = ""
+    @Published var error: String? = nil
+    @Published var showing_wallet_selector: Bool = false
+    @Published var zapping: Bool = false
+    @Published var show_zap_types: Bool = false
+    
+    init() {
+    }
+    
+    func set_defaults(settings: UserSettingsStore) {
+        self.zap_type = settings.default_zap_type
+        self.custom_amount = String(settings.default_zap_amount)
+        self.custom_amount_sats = settings.default_zap_amount
+    }
+}