fix: MM pay request amount used when both paymentProvider and isPostQuote is defined

[jpuri]

Explanation

Fix MM pay request amount used when both paymentOverride and isPostQuote is defined.

References

Related to https://consensyssoftware.atlassian.net/browse/CONF-1520

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

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Note

Medium Risk
Changes payment quote amounts sent to the relay API for a specific MM Pay path; wrong amounts could affect funding quotes, though scope is narrow and well-tested.

Overview
Fixes MetaMask Pay relay quote bodies when paymentOverride is Money Account and isPostQuote is true: the relay request amount for EXACT_OUTPUT now comes from transactionData.tokens[0].amountRaw instead of request.sourceTokenAmount, so the quoted output matches the destination token’s units when decimals differ.

Missing token data falls back to '0'. Tests cover the new amount source, decimal mismatch, and empty/missing transactionData; the package changelog records the fix.

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[jpuri]

request.sourceTokenAmount is raw value of source token and transactionData?.tokens?.[0]?.amountRaw is value in destination token which we need.

Using request.sourceTokenAmount is breaking perps withdraw as USDC has 8 decimal places but mUSD has 6 and relay expect mUSD value here so it result in 100X value of token and hence perps withdraw to Money Balance is failing in latest code.