The dimColor function in packages/core/src/highlight/code-to-tokens-ansi.ts incorrectly parses 4-digit hex colors (RGBA short format, e.g., #1234). It treats them as 3-digit hex colors (RGB short format) and ignores the alpha channel.

Expected Result: #1234 should be expanded to #11223322 (approx).
Actual Result: It is treated as #123, resulting in #11223380.