feat(macos): add native menu bar app with notch overlay

Introduces a SwiftUI companion app for the Fail Well PWA: menu bar
status item, popover with task list / record / history views, command
palette, and a Dynamic Island-style notch overlay that shows the active
step and timer beside the hardware notch and expands on hover to reveal
pause/next controls.

macos/Package.swift

@@ -0,0 +1,24 @@
+// swift-tools-version: 6.0
+import PackageDescription
+
+let package = Package(
+    name: "FailWell",
+    platforms: [.macOS(.v15)],
+    dependencies: [
+        .package(url: "https://github.com/sindresorhus/KeyboardShortcuts", from: "2.3.0")
+    ],
+    targets: [
+        .executableTarget(
+            name: "FailWell",
+            dependencies: [
+                .product(name: "KeyboardShortcuts", package: "KeyboardShortcuts")
+            ],
+            path: "Sources/FailWell"
+        ),
+        .testTarget(
+            name: "FailWellTests",
+            dependencies: ["FailWell"],
+            path: "Tests/FailWellTests"
+        )
+    ]
+)