Proof Request screen — credential matching and selection

### Description
Implement the **Proof Request** screen (`/presentation/request`) — design screen `Desktop-12`.

### UI spec
- Header: `"Proof Request"` with a back `<` button
- Subtitle: `"Select a Credential to present to "`
- A list of matching credentials, each as a card with icon, credential name, and issuer name
- Tapping a credential card selects it and advances to Proof Details
- Bottom navigation bar consistent with the rest of the app

### Acceptance criteria
- [ ] Verifier name is rendered from the parsed authorization request
- [ ] Credential list is populated from stored credentials (mock data for now)
- [ ] Credential matching against `dcql_query` / `presentation_definition` is stubbed — return all credentials as matching initially
- [ ] Selecting a credential navigates to `/presentation/details` with the credential passed as state
- [ ] Empty state handled gracefully (no matching credentials message)