Summary
Improve the integration tests by replacing the current "snapshot and restore" workaround for userConfig with formal dependency injection.

Current Situation
In createDeployment.test.ts, the test for voyageApiKey currently relies on mutating the global userConfig. Because describeWithAtlasLocal doesn't natively support config injection, we are using a beforeEach/afterEach to snapshot and restore the userConfig state. This prevents this specific test from unintentionally affecting other tests in the future.

Goal

• Support explicit dependency injection for userConfig.

• Allow mock configurations to be passed directly into the mock server.

• Remove the need for manual state management (snapshot/restore) in individual test files.

Context

https://github.com/mongodb-js/mongodb-mcp-server/pull/912/changes/BASE..832181a48fbdf1d0c00306b715813b5c7f3144f2#r2833355660