add USDT0 to ink-mainnet whitelist + stables

USDT0 (0x0200C29006150606B650577BBE7B6248F58470c1) is the LayerZero
OFT USDT canonical on Ink. Added to both WHITELIST_TOKENS (tracked
volume/liquidity) and STABLE_COINS (treated as $1 for USD pricing),
matching the pattern on other L2s like tempo.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>