This PR adds the transitive @types/express-serve-static-core dependency as a direct devDependency to fix builds via strict package managers like pnpm. This is necessary because types from express-serve-static-core are currently referenced directly in https://github.com/modelcontextprotocol/typescript-sdk/blob/main/src/server/auth/middleware/bearerAuth.ts#L23-L30

Motivation and Context

Fixes #572

How Has This Been Tested?

• pnpm install + pnpm build on a fresh clone of this branch now succeeds
• rm -rf node_modules/ && pnpm i && pnpm build also succeeds
• Testing for regressions -- rm -rf node_modules/ && npm i && npm run build also succeeds.

Breaking Changes

n/a

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context