fix: correctly identify font-size in font shorthand

[Pixel998]

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AI acknowledgment

• I did not use AI to generate this PR.
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What did you do?

/* eslint css/relative-font-units: "error" */

.a {
  font: oblique 10deg 1rem serif;
}

.b {
  font: 1rem math;
}

What did you expect to happen?

Neither declaration should be reported: 10deg is the oblique angle, and math is a generic font family.

What actually happened?

The rule reported 10deg and math instead of identifying 1rem as the size.

What changes did you make? (Give an overview)

Updated the rule to use the lexer’s font grammar match to identify the actual font-size component before checking whether its unit or keyword is allowed.

Related Issues

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