fix(postcss-hover-classes): avoid large regex overflow by filtering selectors

[EricLLLLLL]

Problem

When using the old postcss-hover-classes plugin, large stylesheets with many :hover selectors caused the following error:

Regular expression too large

This is reported in #1675.

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Solution

This PR rewrites the plugin logic with the following improvements:

• Filters out only :hover selectors before applying replacements
• Uses a WeakSet to ensure we only process each rule once
• Avoids unnecessary string operations and large regex inputs

This not only solves the regex overflow issue but also improves memory efficiency and overall performance when processing large stylesheets.

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Related Issue

Closes #1675