DEV: Update Admin Rule View Border to mediumGray `#CFCFCF`

### Overview

We need to update the color of the Admin Rule View border from `#EEF1F4` to the theme color mediumGray `#CFCFCF`.

### Details

Update the following UI element to use color `mediumGray : "#CFCFCF"`:

- Admin page (navigate to /admin)

Current: Rule view border

### Action Items
- [ ] Assign yourself to the development issue.
- [ ] Move the development issue from the Prioritized Backlog to In Progress.
- [ ] Implement change.
- [ ] Create a PR, if applicable.
- [ ] Create a new slide (or edit one if it already exists) in staging and add the before and after images
- [ ] Once the PR has been approved, use it to close this issue. If there is no PR is associated with this issue, close this issue after lead signoff.

### Resources/Instructions
- This issue is part of an audit of all grays #3319.

#### GithHub
- https://github.com/hackforla/tdm-calculator/blob/develop/client/src/styles/theme.js#L31-L37

#### Staging and Release decks
- [Staging Deck](https://docs.google.com/presentation/d/1crZ3IxqA4hAu3qzD7ns93Ieuqjwh6wyEtuX_46cP-fg/)
- [Staging slide, 3496](https://docs.google.com/presentation/d/1crZ3IxqA4hAu3qzD7ns93Ieuqjwh6wyEtuX_46cP-fg/edit?slide=id.g3fb5ae4c031_1_7#slide=id.g3fb5ae4c031_1_7)
- Release Deck
- [2025-MM-DD Release deck, slide ISSUE NUMBER]

Start with client/src/styles/theme.js at lines 31-37, then navigate to /admin and locate the Admin Rule View border using the existing #EEF1F4 value. Update the border to the mediumGray #CFCFCF theme color and verify the before-and-after appearance in staging, including the issue 3496 slide.

Written by the indexing model from the issue text.