docs: self-service withdrawal guide for deprecated isolated pools

[trumpgpt-bot]

What

Adds HOW-TO-WITHDRAW.md — the user-facing "How to withdraw" doc that the isolated-pools deprecation banner in the dApp will link to (VPD-1777), plus a pointer to it from the README.

Since the dApp is dropping isolated-pool support entirely, calling the contracts directly from a block explorer becomes the only exit path for the remaining position holders. The guide covers it end to end:

• what still works (redeem, repay, claim) and what is disabled (mint, borrow)
• finding your position via Token Holdings or balanceOf / borrowBalanceStored
• repaying with approve + repayBorrow(type(uint256).max) — the contract caps at the actual debt
• withdrawing with redeem(balanceOf), plus redeemUnderlying for partial exits
• optional clean-up: getRewardDistributors → claimRewardToken, unwrapping WBNB/WETH, exitMarket
• troubleshooting keyed to the actual revert names (InsufficientLiquidity, RedeemTransferOutNotPossible, ActionPaused, PriceError)
• a full market reference: Comptroller, vToken, underlying and underlying decimals for every isolated pool on BNB Chain, Ethereum and Arbitrum One

Data

Addresses come from deployments/. Every market's pause state was read on-chain (multicall) on 2026-08-06 — BNB Chain block 114,311,391, Ethereum 25,694,339, Arbitrum One 491,628,878:

• MINT and BORROW are paused in every isolated market; REDEEM, REPAY, TRANSFER and EXIT_MARKET are open.
• Exceptions, flagged in the tables: the matured Pendle PT markets (PT-SolvBTC.BBN-27MAR2025, PT-USDe-27MAR2025, PT-sUSDE-27MAR2025, PT-weETH-26DEC2024), the whole Ethena pool, and rsETH on Ethereum have every action paused. All of those hold zero supply except PT-SolvBTC.BBN-27MAR2025 and rsETH, which hold dust.
• The Core pools on Ethereum and Arbitrum are deployed from this repo but are not deprecated, so they are excluded.

HOW-TO-WITHDRAW.md sits at the repo root rather than in docs/, which is the solidity-docgen output directory.

Notes for review

• Please sanity-check the market statuses before the FE links to this — they are a point-in-time read and governance can change them.
• The paused markets have no self-service exit; the doc routes those users to Discord/Telegram. Worth confirming that is the support path you want named.

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[github-actions]

Package	Line Rate	Branch Rate	Health
contracts	83%	72%	✔
contracts.Gateway	98%	68%	✔
contracts.Gateway.Interfaces	100%	100%	✔
contracts.Lens	95%	69%	✔
contracts.Lens.legacy	0%	0%	❌
contracts.Pool	100%	92%	✔
contracts.Rewards	96%	70%	✔
contracts.Shortfall	100%	85%	✔
contracts.legacy.RiskFund	0%	0%	❌
contracts.lib	100%	89%	✔
Summary	72% (1569 / 2190)	63% (520 / 828)	➖