feat: reserve network fees from native Relay Max (CONF-2006)

[dan437]

Explanation

Relay Max quotes could commit the full native-token balance when the paying account did not support EIP-7702, leaving no funds for source-network fees.

This change re-quotes with the phase-one maximum network fee reserved. ERC-20 payments keep the existing insufficient-native-balance behavior.

References

• CONF-2006

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

---

Note

Medium Risk
Changes max-amount Relay quote math for native-token payments on non-EIP-7702 accounts, which affects how much users can send but improves transaction success.

Overview
Fixes Relay Max quotes that paid with native source tokens on accounts without EIP-7702, where the first quote could spend the entire balance and leave nothing for source-chain gas.

After the initial max quote, the flow now detects native source tokens (chain native address or Relay NATIVE_TOKEN_ADDRESS, e.g. Polygon) and re-quotes with sourceTokenAmount reduced by the phase-one max source-network fee. If reservation is impossible, the adjusted quote fails, or fees eat the whole max, it falls back to the phase-one quote unchanged.

ERC-20 max flows and accounts that support EIP-7702 still use the existing gas-station / native-balance logic; only this native-max + non-7702 branch is new. Tests and the package changelog document the behavior.

^{Reviewed by Cursor Bugbot for commit 63397aa. Bugbot is set up for automated code reviews on this repo. Configure here.}

[cursor]

Current version of PR was reviewed by /review-bugbot on Sep 15, 11:27 GMT+2. It flagged 0 findings.

^{Bugbot on commit b893649 is skipped.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, have a team admin enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit c40a55d. Configure here.}