Fix work minutes calculation to handle same start and end times

[jeyongsong]

This pull request refines the calculation logic for work minutes and daily earnings, especially in cases where the clock-in and clock-out times are the same. It clarifies handling of overnight shifts, ensures accurate time comparisons, and adds corresponding unit tests to verify the new behavior.

Improvements to work time calculation:

• Updated SalaryCalculator.calculateWorkMinutes to treat only cases where clock-out is strictly before clock-in as overnight shifts, and to return 0 minutes when clock-in and clock-out are the same.

Clarifications and fixes to time comparison logic:

• Changed time comparison logic in WorkdayService to use !clockOut.isBefore(clockIn) instead of clockOut.isAfter(clockIn), ensuring correct handling when times are equal. [1] [2]

Test coverage enhancements:

• Added a unit test to SalaryCalculatorTest to verify that identical clock-in and clock-out times return 0 minutes.
• Added a unit test to EarningsCalculatorTest to verify that identical clock-in and clock-out times result in zero earnings.

[github-actions]

Test Results

34 tests   34 ✅  0s ⏱️
 3 suites   0 💤
 3 files     0 ❌

Results for commit 50c91eb.

[Copilot]

Pull request overview

Refines work-time and earnings calculations to correctly handle edge cases where clock-in and clock-out times are identical, aligning “overnight shift” detection to only cases where clock-out is strictly before clock-in.

Changes:

• Updated SalaryCalculator.calculateWorkMinutes to return 0 minutes when clock-in equals clock-out, and treat only strictly-negative durations as overnight shifts.
• Adjusted WorkdayService time comparisons to consider equal times as “not overnight” (!isBefore), preventing incorrect same-time handling.
• Added unit tests covering same clock-in/clock-out behavior for both minutes and earnings calculations.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/test/kotlin/com/moa/service/EarningsCalculatorTest.kt	Adds a unit test ensuring identical clock-in/out results in 0 earnings.
src/test/kotlin/com/moa/entity/SalaryCalculatorTest.kt	Adds a unit test ensuring identical clock-in/out results in 0 work minutes.
src/main/kotlin/com/moa/service/WorkdayService.kt	Updates equality handling in time comparisons to avoid misclassifying equal times as overnight.
src/main/kotlin/com/moa/entity/SalaryType.kt	Updates calculateWorkMinutes logic and KDoc to reflect correct same-time/overnight behavior.

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