🧪 Add test file for ContentView and target to Xcode project

[hatimhtm]

🎯 What: The testing gap addressed
This PR introduces the previously missing test file for ContentView, primarily focusing on verifying that UserDefaults initializes the application's configuration correctly and respects previously established states without regressions. Additionally, it implements the necessary test target inside the Xcode project file Click2Minimize.xcodeproj/project.pbxproj properly integrated with correct frameworks, dependencies, and search paths so that Xcode can automatically locate the XCTest suite to run successfully.

📊 Coverage: What scenarios are now tested

1. Default Initialization behavior: Ensuring that when the user starts the application without an existing .plist default preference, the key ClickToMinimizeEnabled sets to true appropriately.
2. Persistence behavior: Confirming that the initialization does not override UserDefaults if an established value for ClickToMinimizeEnabled already exists (e.g. false).

✨ Result: The improvement in test coverage
We now capture critical initialization state behavior and verify it properly, enabling a fully integrated XCTest target within the Click2Minimize project structure to help prevent unverified application defaults regressions.

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PR created automatically by Jules for task 539922479366199999 started by @hatimhtm

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