Staking UI - escrow, grants, delegation actions and summary

This PR includes:

skale-contracts library integration for all staking-related contract interactions
Updated Start page - added Changelog banner, added Staking card
Added Validatros page with basic validators info
Staking summary for regular accounts, escrow and grant escrow
Escrow info section - vested tokens, unlocked amount, etc
Preview mode to see summary without connecting an actual wallet
Delegation actions - undelegate, cancel pending request, etc
New Changelog page
Validator icons
Updated version of metaport library with improved transaction handling and additional wallet support

Mainnet preview can be found on Vercel.

Tested manually on Testnet and Mainnet contracts, since there are no automated tests for portal repo. No performance changes.

skalenetwork / portal