V5 documentation refresh
- Updated docs for the V5 contract architecture.
- Marked V3 as deprecated/legacy.
- Added OTOInvite referral documentation.
- Updated trading and borrowing fees.
- Added V5 price precision notes.
- Updated create-token flow for optional initial buy.
- Added complete ABI reference pages.
- Updated developer examples for Ethers, Viem, Web3.js, and Python/Web3.py.