[Feature]: candidate metadata — add photo, logo, motto, profile link

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Issue Description ✍️

Extend candidate model and UI so each candidate stores:
IPFS hash for photo and logo (stored on Pinata / IPFS, repo already expects a NEXT_PUBLIC_PINATA_JWT).
motto (short string), bio (longer profile text), website (optional).
Update createCandidate UI to upload assets to IPFS and save the IPFS hashes on-chain (or in the existing backend store).

Why: Improves voter trust & transparency, enables richer candidate pages.

### Record

- [x] I have synced all my node versions as mentioned in the project
- [x] I am using the same version of npm as is the project
- [x] My current branch is in sync with the development branch
- [x] I want to work on this issue