List tasks feature (#4)

This PR contains the work done to implement the **List Tasks** feature, and to integrate it into the main content view of the app.

Reviewed-on: rock-n-code/todos-app#4
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

App/Sources/View Models/TaskListViewModel.swift

@@ -0,0 +1,43 @@
+import SwiftData
+import SwiftUI
+
+extension TaskListView {
+
+    /// View model for managing the logic for the task list view.
+    ///
+    /// This observable class encapsulates the state and business logic for the task list view.
+    /// It follows the MVVM pattern to separate presentation logic from the view layer.
+    ///
+    /// ## Responsibilities
+    /// - Providing the navigation title for the current group
+    @Observable
+    final class ViewModel {
+
+        // MARK: Properties
+
+        /// The task group to display tasks for.
+        ///
+        /// This property determines which tasks are fetched and displayed in the list.
+        private let group: TodoGroup
+
+        // MARK: Initialization
+
+        /// Initializes a new view model instance for a specific task group.
+        ///
+        /// - Parameter group: The task group to display tasks for.
+        init(group: TodoGroup) {
+            self.group = group
+        }
+
+        // MARK: Computed
+
+        /// The navigation title for the current task group.
+        ///
+        /// This computed property provides the localized title for the current group,
+        /// suitable for display in a navigation bar.
+        ///
+        /// - Returns: The localized title key for the current group.
+        var navigationTitle: LocalizedStringKey { group.title }
+
+    }
+}