chore: add virtual flag to overridable functions

[tinom9]

Description

• Add virtual keyword to every function of @layerzerolabs/oft-evm-upgradeable contracts susceptible of being overriden. Excludes init and storage getter functions.

[cursor]

PR Summary

Makes overridable functions explicitly virtual across OFT upgradeable contracts for extensibility; no logic changes.

• Fee config: setDefaultFeeBps, setFeeBps, and _getFeeBps in FeeUpgradeable.sol are now virtual
• Token accessors: token() in OFTUpgradeable, OFTAdapterUpgradeable, and NativeOFTAdapterUpgradeable set to virtual
• Fees APIs: feeBalance() and withdrawFees() in OFTFeeUpgradeable.sol and OFTAdapterFeeUpgradeable.sol set to virtual
• Core: msgInspector() in OFTCoreUpgradeable.sol set to virtual; _payNative() in NativeOFTAdapterUpgradeable.sol now virtual override

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[Copilot]

Pull request overview

This PR adds the virtual keyword to functions in upgradeable OFT contracts that are intended to be overridable by derived contracts, improving extensibility while excluding initialization and storage getter functions.

• Added virtual keyword to public view/pure functions that return contract-specific values
• Added virtual keyword to external functions with access control modifiers
• Added virtual keyword to internal functions that implement overridable behavior

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
OFTUpgradeable.sol	Made token() function virtual to allow customization of token address retrieval
OFTFeeUpgradeable.sol	Made feeBalance() and withdrawFees() virtual to enable custom fee management logic
OFTCoreUpgradeable.sol	Made msgInspector() virtual to allow custom message inspection behavior
OFTAdapterUpgradeable.sol	Made token() function virtual to enable custom token address implementation
OFTAdapterFeeUpgradeable.sol	Made feeBalance() and withdrawFees() virtual to support custom fee handling
NativeOFTAdapterUpgradeable.sol	Made token() and _payNative() virtual to allow customization of native token operations
FeeUpgradeable.sol	Made fee configuration and calculation functions virtual to enable custom fee logic

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[github-actions]

🚨 E2E Tests Failed

The E2E tests failed during CI. These tests validate real blockchain interactions and may fail due to:

• Network connectivity issues
• RPC rate limiting
• External service downtime
  Action Run: https://github.com/LayerZero-Labs/devtools/actions/runs/20449706440

This is non-blocking and does not prevent merging. Check the action logs above for detailed failure information.