Integrate a real-time signature counter component into petition pages.
This includes:
- A new `SignatureCounter` component that displays and animates the
signature count.
- Server action `getSignatureCount` to fetch current signatures from
Payload.
- Updates to `submitPetitionSignature` to return the signature number
for immediate display.
- Event listeners for real-time updates when new signatures are
submitted.
- Integration of the counter into both the hero section and card views
of the petition page.
- Improved dialog for displaying signature success and number.
