Updated the `EnvelopeViewer` component to improve the user interface and functionality:
- Added `EnvelopeReceiverService` injection to fetch receiver data.
- Redesigned `envelope-action-bar` for better alignment and responsiveness.
- Displayed dynamic document title and compact badges for receiver info, sender name, signature count, and security features (e.g., access code, 2FA).
- Refactored logout button styling and `envelope-content` layout.
- Introduced `_envelopeReceiver` field and updated `SignatureService.GetAsync` to fetch receiver data.
- Added debugging logs for loaded signatures.
- Added fields for managing signature navigation state.