Add transaction pay quote usability fallback

[pedronfigueiredo]

Description

This follow-up keeps the Transaction Pay fallback principle intact after provider quotes are constructed. A strategy can now return technically supported quotes but still be skipped if those quotes are unusable for the current account context, such as when they require origin native gas that the account cannot pay.

The quote loop now checks strategy support, fetches quotes, checks provider quote support, then runs a normalized quote usability check before selecting the strategy. If the first strategy is unusable, the controller logs the reason and continues to the next configured strategy. This lets Across remain first when the account can complete the route, while allowing Relay to win when it can provide a gasless path for the same situation.

Changes

• Added checkQuoteUsability to evaluate quote requirements against native source-chain balance.
• Continued strategy fallback when a quote requires origin native gas that the account cannot cover.
• Preserved the existing post-quote provider support check for authorization-list limitations.
• Added regression coverage for Across-to-Relay fallback and for Across still winning when the account can pay origin gas.
• Added direct quote-usability coverage for authorization-list, native-source, non-object original quote, invalid amount, and missing amount branches.

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Note

Medium Risk
Changes strategy selection logic in the quoting loop, which can alter which provider is chosen for a transaction and may impact payment routing in edge cases around native gas requirements.

Overview
Adds checkQuoteUsability to validate returned quotes against account constraints (authorization-list requirements and whether sufficient native source-chain balance exists to cover required origin gas and/or native source token amounts).

Updates the quote-strategy loop in quotes.ts to run this usability check after provider quote support checks; if unusable it logs the reason and continues to the next configured strategy (e.g., allowing Across→Relay fallback when the account can’t pay origin gas). Tests are expanded with new unit coverage for the usability rules and for the new fallback behavior, and the changelog documents the fix.

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