feat: add transactions infinite query option

[n3ps]

Explanation

This PR adds a new getV4MultiAccountTransactionsInfiniteQueryOptions method to AccountsApiClient that is designed specifically for useInfiniteQuery consumers:

• Stable query key: Excludes pagination params from the query key so it remains stable across all pages.
• Runtime pagination via pageParam: The queryFn accepts pageParam and maps it to the cursor API parameter, rather than closing over a fixed cursor value.

Extension consumption:

const queryOptions = apiClient.accounts.getV4MultiAccountTransactionsInfiniteQueryOptions({
  accountAddresses: ['eip155:0:0xabc...'],
  networks: ['eip155:1', 'eip155:137'],
  includeTxMetadata: true,
});

useInfiniteQuery({
  ...queryOptions,
  // example:
  select: myCustomTransform,
});

References

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

Low Risk
Low risk: adds a new query-options helper and tests without changing existing transaction fetch behavior; main risk is cache-key semantics for useInfiniteQuery consumers.

Overview
Adds AccountsApiClient.getV4MultiAccountTransactionsInfiniteQueryOptions to produce TanStack useInfiniteQuery-friendly options for the v4 multi-account transactions endpoint, using pageParam as the cursor and a stable queryKey that sorts accountAddresses/networks.

Extends unit tests to validate query key stability and default/override cache timings, and documents the new helper in the core-backend changelog.

^{Written by Cursor Bugbot for commit a5dcb5a. This will update automatically on new commits. Configure here.}