[VPD-1185] feat: add TokenBuyBack deployments on bsctestnet

[Debugger022]

Summary

• Deploy 10 TokenBuyback instances (RiskFund, XVS, Prime, Treasury variants) on bsctestnet and register their addresses.
• Add a reusable verifyDeployment helper and wire it into every deploy script so proxy + implementation get verified on BscScan automatically.
• Update hardhat config to use DEPLOYER_PRIVATE_KEY for bsctestnet and pull in @venusprotocol/venus-protocol external deployments; redeploy RiskFundV2 implementation.

Changes

Deploy scripts

• deploy/000-psr.ts … deploy/009-treasury-buyback.ts: switch handlers to receive hre directly and call verifyDeployment(hre, name) after deployment / ownership transfer for ProtocolShareReserve, RiskFundV2, RiskFundConverter, XVSVaultTreasury, SingleTokenConverterImp, SingleTokenConverterBeacon, all SingleTokenConverter instances, ConverterNetwork, RiskFundBuyback, all Prime/Treasury TokenBuyback instances, and XVSBuyback.

Verification helper

• helpers/verify.ts (new): exports verifyDeployment / verifyDeployments. Skips hardhat / localhost, skips when ETHERSCAN_API_KEY unset, verifies _Implementation + _Proxy (or main artifact when neither exists), tolerates "already verified" responses, logs failures without throwing.

Hardhat config

• hardhat.config.ts: add node_modules/@venusprotocol/venus-protocol/deployments/bsctestnet to externalDeployments.bsctestnet; bsctestnet accounts now uses DEPLOYER_PRIVATE_KEY instead of the mnemonic.

Deployments (bsctestnet)

• New TokenBuyback proxy + implementation artifacts and address-registry entries:
  • RiskFundBuyback — proxy 0x1a063a…71fE, impl 0x9A3716…86D8
  • XVSBuyback — proxy 0x7b96F9…5a11, impl 0x8a5E9a…c343
  • UPrimeBuyback — proxy 0xa9f091…07a4, impl 0x26C451…e1d7
  • USDTPrimeBuyback — proxy 0xaAc507…ab55, impl 0x9Ae32e…fadB
  • BTCBTreasuryBuyback — proxy 0x3AC5D1…feb6, impl 0x95d174…89Dd
  • ETHTreasuryBuyback — proxy 0x721CCA…C35d, impl 0x766fd2…8884
  • USDCTreasuryBuyback — proxy 0x90814c…0fF3, impl 0x03EFea…6573
  • USDTTreasuryBuyback — proxy 0xBCF3Ef…a497, impl 0xA65f35…29F5
  • UTreasuryBuyback — proxy 0x281d53…0C5C, impl 0xDBE338…3412
  • XVSTreasuryBuyback — proxy 0x9d8d03…E773, impl 0xC0C38f…9361
• Redeploy RiskFundV2_Implementation → 0xAAe9c6412A7EaeB82eD2bA8E9E2bBc27bDa921f6.
• Update deployments/bsctestnet.json and deployments/bsctestnet_addresses.json accordingly.

Test plan

• yarn hardhat compile clean.
• yarn hardhat deploy --network bsctestnet --tags RiskFundBuyback,XVSBuyback,PrimeBuyback,TreasuryBuyback is a no-op (skipIfAlreadyDeployed) and re-runs verifyDeployment without errors.
• All 20 buyback artifacts (10 impl + 10 proxy) show as verified on BscScan testnet (confirmed via Etherscan v2 API, chainid 97 — impls = TokenBuyback, proxies = OptimizedTransparentUpgradeableProxy).
• RiskFundV2_Implementation at 0xAAe9c6412A7EaeB82eD2bA8E9E2bBc27bDa921f6 verified on BscScan.
• Address registry deployments/bsctestnet_addresses.json contains all new entries with matching _Proxy / _Implementation pairs.

[github-actions]

Package	Line Rate	Branch Rate	Health
Interfaces	100%	100%	✔
ProtocolReserve	95%	78%	✔
Test	100%	100%	✔
Test.Mocks	65%	44%	➖
TokenConverter	89%	74%	✔
Utils	100%	100%	✔
Summary	89% (694 / 780)	74% (241 / 324)	✔