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'@modelcontextprotocol/server': patch
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Add `| undefined` to optional callback and function properties on `WebStandardStreamableHTTPServerTransportOptions` (`sessionIdGenerator`, `onsessioninitialized`, `onsessionclosed`) and corresponding private fields.

This fixes TS2430 errors for consumers using `exactOptionalPropertyTypes: true` without `skipLibCheck`, where optional properties with function types need explicit `| undefined` to match their emitted declarations.