[release/3.6] 添加“提前预览 HMCL 版本”选项

[Glavo]

#4223
#4598
#4599

[Copilot]

Pull Request Overview

This PR adds a new "Preview HMCL releases early" option to the settings that allows users to receive pre-release versions of HMCL for testing before their official release. The implementation includes UI changes, configuration updates, and modifications to the update checking mechanism.

• Adds a new toggle button in settings to enable/disable preview updates
• Modifies the update checker to support preview versions by appending "-preview" to the channel name
• Updates the upgrade dialog to handle preview-specific changelog sections
• Adds localization strings for the new feature in multiple languages

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
I18N*.properties	Adds localization strings for the preview update feature in English, Spanish, and Chinese variants
UpdateChecker.java	Modifies update checking logic to support preview versions and pass preview flag through the system
RemoteVersion.java	Adds preview field to track whether a version is a preview release
SettingsView.java	Adds the preview toggle button UI component to the settings panel
SettingsPage.java	Binds the preview toggle to update checking logic with proper event handling
UpgradeDialog.java	Updates changelog handling to show preview-specific content when available
Config.java	Adds configuration property to persist the preview update preference

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