Fix Swift concurrency warnings and add README

Author: Pablo-Merino

OSView/OSViewApp.swift

@@ -42,12 +42,11 @@ struct OSViewApp: App {
 
 // MARK: - App Delegate for additional window configuration
 
+@MainActor
 class AppDelegate: NSObject, NSApplicationDelegate {
     func applicationDidFinishLaunching(_ notification: Notification) {
         // Configure main window after launch
-        DispatchQueue.main.async {
-            self.configureMainWindow()
-        }
+        configureMainWindow()
     }
 
     func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {

README.md

@@ -0,0 +1,48 @@
+# OSView
+
+A native macOS system monitoring utility built with SwiftUI. Displays real-time metrics for CPU, memory, GPU, disk, and network.
+
+## Requirements
+
+- macOS 15.0 or later
+- Xcode 16+ (for building from source)
+
+## Installation
+
+### Download
+
+Download the latest release from the [Releases](../../releases) page.
+
+**Note:** The app is unsigned. On first launch, you'll need to:
+1. Right-click (or Control-click) on `OSView.app`
+2. Select "Open" from the context menu
+3. Click "Open" in the dialog that appears
+
+This is only required once. macOS will remember your choice.
+
+### Build from Source
+
+```bash
+git clone https://github.com/yourusername/OSView.git
+cd OSView
+xcodebuild -project OSView.xcodeproj \
+  -scheme OSView \
+  -configuration Release \
+  -derivedDataPath build \
+  clean build
+```
+
+The app will be at `build/Build/Products/Release/OSView.app`.
+
+## Why is the app unsigned?
+
+Signing and notarizing macOS apps requires a paid Apple Developer Program membership ($99/year). Since this is an open-source project, the app is distributed unsigned.
+
+This means:
+- macOS Gatekeeper will show a warning on first launch
+- You need to right-click → Open to bypass the warning (one time only)
+- The app works normally after that
+
+## License
+
+MIT