The commit implements cross-page navigation for signatures in the `EnvelopeViewer.razor` component. Users can now navigate between signatures across pages using "Next Signature" and "Previous Signature" buttons.
Key changes:
- Fixed `getSignatureNavState()` to correctly calculate total, signed, and unsigned signatures globally.
- Updated `goToNextSignature()` to navigate to the next unsigned signature, including automatic page changes and scrolling.
- Updated `goToPreviousSignature()` to navigate to the last signed signature, including automatic page changes and scrolling.
- Ensured navigation buttons are properly disabled when no further navigation is possible.
The toolbar design remains unchanged, as requested. These changes address issues caused by a previous implementation that broke the counter and navigation functionality.
