v0.30.2 — neg-risk trading fix (pUSD→NegRisk Adapter approval)

Fixes real-money trading on neg-risk (multi-outcome "winner") markets.

• fix(polymarket) — grant the missing pUSD → NegRisk Adapter approval. setup approved pUSD spend for only the two exchanges while giving the adapter a CTF operator approval but not the pUSD one — so a funded, exchange-approved vault had its neg-risk orders accepted by the CLOB then reverted in settlement. The pUSD spender set now matches Polymarket's canonical approveTokensForTrading (both exchanges + NegRisk Adapter + Conditional Tokens). Existing deposit wallets self-correct: re-run action:"setup" confirm:true once to sign the new approval.
• fix(polymarket) — buy/sell now self-heal a stale CLOB balance cache: on a not enough balance/allowance rejection, refresh updateBalanceAllowance and retry the submit once; setup no longer silently swallows a failed cache warm-up.
• docs — document the full canonical approval set + neg-risk troubleshooting (README, setup guide, skill).

152 tests, typecheck, build, and stdio MCP smoke (19 tools) green.