Add USDT0 OFT adapter

[lastperson]

Closes: #174

[Copilot]

Pull request overview

Adds USDT0 bridging support to the Repayer via a new LayerZero OFT-based adapter, including unit tests and fork tests, and updates deployment/upgrade scripts to pass the new configuration parameter.

Changes:

• Introduce USDT0Adapter + IOFT/ILayerZero interfaces and add Provider.USDT0 routing in Repayer.
• Refactor Stargate endpoint ID mapping into a shared LayerZeroHelper used by multiple adapters.
• Add unit + fork tests and extend deployment/upgrade scripts/config to include USDT0OFT.

Reviewed changes

Copilot reviewed 27 out of 27 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
contracts/Repayer.sol	Adds USDT0Adapter inheritance and dispatch for Provider.USDT0.
contracts/utils/USDT0Adapter.sol	New adapter to send USDT0 via LayerZero OFT.
contracts/utils/LayerZeroHelper.sol	Centralizes LayerZero endpoint-id mapping.
contracts/utils/StargateAdapter.sol	Switches to LayerZeroHelper mapping for dstEid.
contracts/interfaces/IOFT.sol	New minimal OFT interface used by USDT0 adapter/tests.
contracts/interfaces/ILayerZero.sol	New shared structs for LayerZero/OFT operations.
contracts/interfaces/IStargate.sol	Reuses LayerZero structs via import instead of redefining.
contracts/interfaces/IRoute.sol	Extends Provider enum with USDT0.
contracts/testing/TestUSDT0OFT.sol	Adds test token + OFT adapter/native mocks for unit tests.
contracts/testing/TestRepayer.sol	Updates constructor args to include usdt0Oft.
test/Repayer.ts	Updates constructor arg count, renames endpoint getter, adds USDT0 unit tests.
specific-fork-test/ethereum/RepayerUSDT0.ts	New Ethereum fork test for USDT→USDT0 OFT flow.
specific-fork-test/unichain/RepayerUSDT0.ts	New Unichain fork test for USDT0 bridging.
specific-fork-test/arbitrum/RepayerUSDT0.ts	New (skipped) Arbitrum fork test for USDT0 bridging.
specific-fork-test/polygon/RepayerUSDT0.ts	New (skipped) Polygon fork test for USDT0 bridging.
specific-fork-test/gnosis/RepayerGnosisOmnibridge.ts	Updates Repayer constructor arg list (adds ZERO_ADDRESS).
specific-fork-test/ethereum/RepayerGnosisOmnibridge.ts	Updates Repayer constructor arg list (adds ZERO_ADDRESS).
specific-fork-test/ethereum/Repayer.ts	Updates Repayer constructor arg list (adds ZERO_ADDRESS).
scripts/deploy.ts	Passes USDT0OFT into Repayer deploy args and defaults to ZERO_ADDRESS.
scripts/deployRepayer.ts	Passes USDT0OFT into Repayer deploy args and defaults to ZERO_ADDRESS.
scripts/deployStandaloneRepayer.ts	Passes USDT0OFT into Repayer deploy args and defaults to ZERO_ADDRESS.
scripts/upgradeRepayer.ts	Passes USDT0OFT into Repayer upgrade args and defaults to ZERO_ADDRESS.
scripts/common.ts	Adds ProviderSolidity.USDT0 mapping.
network.config.ts	Adds USDT0OFT addresses per-network.
package.json	Adds fork-test scripts for Arbitrum/Polygon/Unichain.
.env.example	Adds fork-test env vars for USDT/USDT0 holders.
coverage-baseline.json	Updates stored coverage baseline values.

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