Darken Font for Locked Values

Title of ticket:

#### Description
Have received feedback from users that the light grey font used to denote a locked field (eg. approved fee estimates, request details) can be difficult to read for some users - a darker font would be preferred.

#### Dependencies
Are there any dependencies?

#### DOD
- [ ] Approved Fee Estimate Field fonts darkened
- [ ] Locked Request Detail Field Fonts darkened
- [ ] Other?

Start by locating the approved fee estimate and locked request detail fields in the frontend, then inspect the styles that control their light grey text. Update the relevant styling so both field types use a darker, readable font, and verify each item in the DOD checklist, including whether any other locked fields need the same treatment.

Written by the indexing model from the issue text.