fix(stellar-wallet-snap): satisfy price refresher typecheck

[ulissesferreira]

Explanation

ConfirmationPriceRefresher reduces prices into ContextWithPrices['tokenPrices'], whose type is a required Stellar asset-ID record. The empty reducer initializer was inferred as {}, causing the Stellar package typecheck to fail.

This restores the explicit accumulator type assertion so the reducer initializer matches the declared accumulator type.

References

• Fixes the typecheck failure introduced while moving the Stellar snap into packages/.

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