v15.54.2

## What's Changed
* Disables _Overwrite Salary Structure Amount_ in **Additional Salary** when the selected component is not part of the employee’s salary structure and treats missing amounts as zero, preventing salary slip errors. (https://github.com/frappe/hrms/pull/3898)
* Fixes calculation in **Salary Slip** so that when an _Additional Salary_ entry sets a component’s amount to 0, the slip now shows 0 instead of a negative value. (https://github.com/frappe/hrms/pull/3902)


**Full Changelog**: https://github.com/frappe/hrms/compare/v15.54.1...v15.54.2
**Authors**: @venkat102, @asmitahase, @nareshkannasln
**Reviewers**: @asmitahase

<details>
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 For these release notes, we used an LLM (OpenAI o3) to review and summarise the code changes, along with the associated issue and PR descriptions. It may contain typical errors and inaccuracies. You can read the prompt [here](https://github.com/barredterra/pretty_release_notes). 

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