New task feature (#2)

This PR contains the work done to implement the **New Task** feature, and to integrate it into the main context view of the app.

Reviewed-on: rock-n-code/todos-app#2
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

App/Sources/Models/Item.swift

@@ -1,11 +0,0 @@
-import Foundation
-import SwiftData
-
-@Model
-final class Item {
-    var timestamp: Date
-
-    init(timestamp: Date) {
-        self.timestamp = timestamp
-    }
-}

App/Sources/Models/Todo.swift

@@ -0,0 +1,42 @@
+import Foundation
+import SwiftData
+
+/// Represents a todo task created by a user.
+@Model
+final class Todo {
+
+    // MARK: Properties
+
+    /// A date when the todo was completed, if applicable.
+    var completed: Date?
+
+    /// A date by which the todo should be completed.
+    var due: Date
+
+    /// An optional note providing additional details about the todo task.
+    var note: String?
+
+    /// The title of the todo task.
+    var title: String
+
+    // MARK: Initializers
+
+    /// Creates a new todo item.
+    /// - Parameters:
+    ///   - title: The title of the todo item.
+    ///   - note: An optional note providing additional details.
+    ///   - due: The date by which the todo should be completed.
+    ///   - completed: The date when the todo was completed, if applicable.
+    init(
+        title: String,
+        note: String? = nil,
+        due: Date,
+        completed: Date? = nil
+    ) {
+        self.completed = completed
+        self.due = due
+        self.note = note
+        self.title = title
+    }
+
+}