Add empty state content to "Contacts"

### What is this about?

To encourage users to add more petnames and to enhance the consistency in empty states across wallet

### Scenario

When users are clicking through different settings in mobile and encounter a blank page in contacts.

### Design

Suggestion: [](https://www.figma.com/design/MWSp7bsEIWubkf5BVYJlMC/Design-audit---Saya?node-id=2-718&t=wqpqrhd75a7oeMuM-1)

### Technical Details

_No response_

### Threat Modeling Framework

_No response_

### Acceptance Criteria

_No response_

### Stakeholder review needed before the work gets merged

- [ ] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)

### References

_No response_

Start by reviewing the linked Figma design and locating the mobile Contacts screen in the repository; the issue names no files, entry points, or tests. Confirm the intended empty-state wording and layout, then verify that the Contacts page displays the approved content when no petnames exist.

Written by the indexing model from the issue text.