feat: support lts releases in linux

[risu729]

It was unable to install LTS versions of PHP because it was not listed in https://www.php.net/releases/, which only includes "Unsupported Historical Releases".

$ vfox --debug install [email protected]
CallFunction: PreInstall
plugin [PreInstall] method error: /home/risu/.version-fox/plugin/php/hooks/pre_install.lua:31: version not found for provided version 8.4.8
stack traceback:
        [G]: in function 'error'
        /home/risu/.version-fox/plugin/php/hooks/pre_install.lua:31: in main chunk
        [G]: ?
failed to install php

This PR adds https://www.php.net/downloads.php as the source of versions to support LTS versions.

[Copilot]

Pull Request Overview

This PR adds support for LTS (Long Term Support) PHP releases on Linux by incorporating the downloads page as an additional source for version information. Previously, only versions from the releases page were available, which excluded current LTS versions.

• Restructured URL constants to support both standard releases and LTS downloads pages
• Updated Linux version discovery to check both releases and downloads pages
• Modified Windows release handling to use renamed constants

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
lib/constants.lua	Restructured URL constants to separate standard and LTS release URLs
hooks/pre_install.lua	Updated Windows release URL references to use renamed constants
hooks/available.lua	Enhanced Linux version discovery to fetch from both releases and downloads pages

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[Copilot]

The conditional logic for extracting version strings is unclear. Consider extracting this into separate functions for LTS and standard release parsing to improve readability and maintainability.

[Copilot]

The CSS selector construction using string concatenation with conditional logic makes the code harder to understand. Consider defining separate constants for the selectors or extracting this into a helper function.