Add configurable fade in/out animations

[Copilot]

Implements fade transitions for the Launchpad window to match macOS Sequoia's native Launchpad behavior. Requested as a configurable option since the abrupt show/hide felt off compared to the original.

Implementation

• Settings: Added enableFadeAnimation: Bool to LaunchpadSettings (default: true)
• UI: Added toggle in Features settings tab with English/Hungarian localization
• Animation: Window opacity transitions 0→1 on show, 1→0 on hide (0.3s ease-in-out)
• Architecture: Callback pattern (AppLauncher.onExitRequested, AppDelegate.onExitRequested) decouples animation from app lifecycle
• Performance: When disabled, uses nil animation for instant show/hide

Key Changes

LaunchpadApp.swift

• Added @State windowOpacity for animation control
• Fade in on initialization and app reactivation (via NSApplication.didBecomeActiveNotification)
• handleExitRequest() fades out before hiding (delay matches animation duration)
• Weak self capture in notification observer to prevent retain cycle

AppLauncher.swift

• Callback mechanism allows UI layer to animate before NSApp.hide()
• New hideImmediately() for post-animation hiding

LaunchpadConstants.swift

• Added fadeAnimationDuration: TimeInterval = 0.3 (synced with existing fadeAnimation)

Example Flow

// Fade out sequence
private func handleExitRequest() {
   if settingsManager.settings.enableFadeAnimation && windowOpacity > 0 {
      windowOpacity = 0.0  // SwiftUI animates over 0.3s
      DispatchQueue.main.asyncAfter(deadline: .now() + LaunchpadConstants.fadeAnimationDuration) {
         AppLauncher.hideImmediately()
      }
   } else {
      AppLauncher.hideImmediately()  // Instant for disabled state
   }
}

Testing

Added FadeAnimationSettingsTests.swift with 15 test cases covering persistence, encoding/decoding, defaults, and integration.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add options for fade in/out animations</issue_title>
<issue_description># Description :
Been using it for quiet a while as its the best replacement I've found so far but something felt off about the way the interface is opened and closed so I compared it to my Mac running Sequoia which has the OG Launchpad and noticed it has a fade in an out Animation which LaunchpadPlus seems to lack.

I'd say adding that would allow it to be alot more authentic but preferably let that be a configurable option or disabled entirely who knows if everyone wants it or not.

Plattform Infos :

Host : Macbook Pro M5
OS : MacOS TheHoe 26.1 (25B78)
LaunchpadPlus Branch : main</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add options for fade in/out animations #93

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