Fix mouse wheel paging and restore classic Launchpad background interactions

[CannonTang]

Summary

This PR fixes Launchpad mouse wheel paging behavior and restores several classic Launchpad interaction patterns through focused settings.

Changes

Mouse wheel paging fix

• Fixes paging input so standard mouse vertical wheel scrolling works as expected.
• Uses automatic input handling:
  • non-continuous mouse wheel input pages with the vertical wheel
  • continuous gesture input pages only after a stable horizontal gesture is detected
• Adds defensive gesture state reset handling to avoid stale scroll state after cancelled or momentum scroll phases.

Classic wallpaper blur background

• Adds a background image source option:
  • Live desktop
  • Wallpaper image
• Restores a wallpaper-based blurred background mode for users who prefer the older Launchpad-style look.
• Adds a blur strength slider for wallpaper mode.

Quick compact-layout action

• Adds an optional quick action button to compact icons and automatically fill empty slots.
• Exposes the button in Settings, similar to the existing quick refresh button.
• Implements this as a separate action path without replacing the existing compact-within-pages logic.

Close on blank-area click

• Adds an optional setting to close Launchpad when the user left-clicks an empty area.
• This improves parity with the classic fullscreen Launchpad dismissal behavior.

Notes

• Scroll input is handled automatically to keep mouse wheel and gesture paging behavior intuitive.
• No local-only project configuration changes are included in this PR.

Development / Release Environment

Development and local verification environment:

• macOS 27.0 (26A5353q)
• Xcode 27.0 beta (27A5194q) from /Users/windbylocus/Downloads/Xcode-beta.app
• Apple Silicon / arm64

Fork release environment:

• The fork release build is ad-hoc signed and not notarized.
• The fork release asset is Apple Silicon / arm64 only because my current macOS 27 + Xcode 27 beta release environment can only produce an Apple Silicon local release build.
• This release limitation applies only to my fork release asset and is not intended to change upstream architecture compatibility.

Testing

Tested locally with:

• mouse vertical wheel paging
• horizontal gesture paging
• wallpaper background mode with blur strength adjustment
• quick compact-layout action
• blank-area click dismissal

Build verified with:

• xcodebuild -scheme LaunchNext -configuration Debug
• xcodebuild -scheme LaunchNext -configuration Release

[CannonTang]

English:

A test build is available from my fork release for anyone who wants to try these changes before the PR is reviewed/merged:

https://github.com/CannonTang/LaunchNext/releases/tag/cannon-2026.06.12

Feedback is welcome, especially around mouse wheel paging, horizontal gesture paging, wallpaper blur background, the compact-layout button, and blank-area click dismissal.

Note: this build is ad-hoc signed and not notarized with an Apple Developer ID. On first launch, macOS may require approving it from System Settings > Privacy & Security > Open Anyway.

Release environment note: this fork release asset is Apple Silicon / arm64 only. My current macOS 27 + Xcode 27 beta release environment can only produce an Apple Silicon local release build. This limitation only applies to my fork release asset and is not intended to change upstream architecture compatibility.

中文：

我在自己的 fork release 里放了一个测试构建，欢迎任何人在 PR 审查/合并前下载测试：

https://github.com/CannonTang/LaunchNext/releases/tag/cannon-2026.06.12

欢迎反馈，尤其是鼠标滚轮翻页、横向手势翻页、壁纸模糊背景、一键整理按钮、点击空白处关闭这些功能。

注意：这个构建是 ad-hoc 签名，没有 Apple Developer ID 公证。首次打开时，macOS 可能需要在 系统设置 > 隐私与安全性 中点击“仍要打开”。

发布环境说明：这个 fork release 资产仅支持 Apple Silicon / arm64。因为我当前的 macOS 27 + Xcode 27 beta 发布环境只能产出 Apple Silicon 本地发布包。这个限制只适用于我的 fork release 资产，不代表要改变上游项目的架构兼容性。