Function formatDate

formatDate(date?, options?): string
Formats a date according to the specified dateStyle and locale.

Uses Intl.DateTimeFormat internally.
- "short" uses a custom format: dd/mm/yyyy (e.g., 31/12/2025)
- Other styles use built-in Intl formatting
Example Output
```
formatDate(new Date("2025-12-31"), { dateStyle: "short" });  // "31/12/2025"
formatDate(new Date("2025-12-31"), { dateStyle: "medium" }); // "Dec 31, 2025"
formatDate(new Date("2025-12-31"), { dateStyle: "long" });   // "December 31, 2025"
formatDate(new Date("2025-12-31"), { dateStyle: "full" });   // "Wednesday, December 31, 2025"
```
Parameters
- Optional date: number | Date
  The date object or timestamp to format.
- options: FormatDateOptions = ...
  Options to customize formatting.
Returns string
A formatted date string.