More built-in functions: ROUND(), MOD(), MAX(), MIN(), TIME(), YEAR()/MONTH()/DAY()

[DDecoene]

The expression engine supports 20+ built-ins (src/interpreter/Builtins.ts) but is missing several dBASE III standards:

• ROUND(n, decimals)
• MOD(a, b)
• MAX(a, b) / MIN(a, b)
• TIME() — current time as HH:MM:SS
• YEAR(date), MONTH(date), DAY(date) — numeric date parts

Builtins.ts functions are stateless and individually tiny — a great first contribution. Add each with a Vitest case (see existing function tests for the pattern). Picking just one or two of these is a perfectly fine PR.

[kas2804]

hey @DDecoene can i please take up this issue?

[Aditijainnn]

@DDecoene Hi! I'd like to contribute to this issue.

[DDecoene]

Thanks both! @kas2804 you asked first, so this one's yours — go for it 🎉 It's six functions, so feel free to split them across a couple of PRs if that's easier.

@Aditijainnn really appreciate the interest! Would you like to take #2 (the ? print command) or #3 (SUM/AVERAGE)? Both are good first issues and unclaimed — just say the word and they're yours.