Fix broken LayerZero links and update Goerli to Sepolia

- Update LayerZero documentation links to V2 structure
- Replace Base Goerli/Optimism Goerli with Base Sepolia/Optimism Sepolia
- Update RPC URLs, endpoint addresses, and endpoint IDs for Sepolia testnets
- Fix broken LayerZero endpoint documentation links
- Update Foundry documentation link to new structure

Addresses the exact changes from PR base#273 with verified commits.

Author: Bvvvp009