Support 3-digit shorthand hex colors in templates

[mahmoodhamdi]

While using chalk-template for a terminal dashboard, I noticed that 3-digit shorthand hex colors like {#F00 text} throw an error, even though chalk itself supports chalk.hex('#F00').

Before: {#F00 hello} → Unknown Chalk style: undefined
After: {#F00 hello} → works, same as {#FF0000 hello}

The fix updates the style regex to match 3-digit hex and expands shorthand digits in parseHex (F00 → FF0000), matching chalk's own behavior.

Supported:

• Foreground: {#F00 text}
• Background: {#:0F0 text}
• Both: {#F00:0F0 text}
• Mixed with 6-digit: {#F00:00FF00 text}
• Chained with modifiers: {bold.#F00 text}

All existing tests pass, new tests added for both tagged template and template() function.

[sindresorhus]

I think this introduces a regression for invalid hex lengths. I manually checked {#FFFF hello} and {#:FFFF hello} on main and both still throw Unknown Chalk style: undefined, but on this branch they now render plain hello instead. So malformed 4 or 5 digit hex values get partially matched as 3 digit hex and the styling is silently ignored, which seems like a behavior change in the error path.

Could you tighten the parsing so the whole hex token has to match, and add a couple of tests for invalid 4 and 5 digit values?