Fixes Issue #2750 : Inconsistent Behavior with duration.weeks()

[github-roushan]

This commit fixes the open issue #2750

Problem

The inconsistency occurs due to the following reasons:

1. The weeks property behaves like asWeeks() for all units except milliseconds or weeks.
2. The add functionality for duration.weeks() was missing.

Fix

• Updated the logic to ensure weeks behaves consistently across all units.
• Implemented the missing add functionality for duration.weeks().
• Modified and expanded test cases to reflect these changes.

Verification

For example, 1000000000 milliseconds equals:

• 1 week, 4 days, 13 hours, 46 minutes, and 40 seconds (validated via [MilliSecond Converter].

This matches the output of the following code:

dayjs.extend(duration);
const tmpDur = dayjs.duration(1000000000);
console.log(tmpDur);

Result:

l {
  '$d': {
    years: 0,
    months: 0,
    days: 11,
    hours: 13,
    minutes: 46,
    seconds: 40,
    milliseconds: 0
  },
  '$l': 'en',
  '$ms': 1000000000
}

Modified Test Case

• Demonstrates that adding 1 week to a duration now works as expected.

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Let me know if further adjustments are needed!