feat(duration): parse time strings (HH:mm:ss) into durations

[hamzahamidi]

Summary

Adds support for Moment-compatible colon-separated duration string parsing to the duration plugin. Closes #1146.

This lets Day.js parse duration strings such as:

dayjs.duration('02:04:33')
dayjs.duration('23:59')
dayjs.duration('7.23:59:59')
dayjs.duration('23:59:59.999')
dayjs.duration('-23:59:59')

Changes

When ISO 8601 duration parsing does not match a string input, Day.js now tries the same colon-separated duration syntax supported by Moment.js:

• HH:mm
• HH:mm:ss
• days.HH:mm:ss
• fractional seconds, e.g. 23:59:59.999
• signed values, e.g. -23:59:59

Fractional seconds are converted to milliseconds so existing duration accessors such as .seconds() and .milliseconds() continue to behave correctly.

Scope

This PR adds Moment-compatible duration string syntax parsing; it does not attempt to make all Day.js duration behavior identical to Moment.js.

Parsing is automatic for the single-argument form:

dayjs.duration('02:04:33')

The two-argument form from #1146:

dayjs.duration('02:04:33', 'HH:mm:ss')

is intentionally not added. In Day.js, the second argument is already the duration unit, and Moment.js also supports these colon-separated strings through automatic single-argument detection.

Validation

• npx jest test/plugin/duration.test.js
• 36 tests passed (6 new, 30 existing)
• Full Lint and Unit Test GitHub Actions workflow passes