Implement changes from 2026 salary negotiations

This is a scheduled issue to implement changes arising from the 2026 pay negotiations.

Please note, whoever picks this issue up should create a copy of this issue for 2027 with a due date set to 2027-09-01

Technical Notes

The actual job requires that you add the figures from the All Grades (Excel) spreadsheet (not currently, but published elsewhere as per the comment below) on the HR salary scales page to the module's salary_scales.yaml file.

Please remember to add a version tag to your commit and then raise MRs on the webapp and salaries-commitments projects to deploy the resulting changes. Link the MR's to this issue.

Note: By the time this comes around, we hope that the salary data will be directly uploaded into the salary with on-costs service from HR, rather than us importing it manually, and Research Dashboard will use the API on the on-costs service for performing its calculations. This ticket exists in case other priorities have prevented us from doing that before then