Change sample server host from 0.0.0.0 to 127.0.0.1

[JLLeitschuh]

Don't bind the sample server to 0.0.0.0 by default as that exposes the server to anyone else on the local network.

If anyone were to use these samples as staring points to build larger services, those servers would thus expose developers to attack immediately upon launch.

I'd prefer if we avoided that 😆

Motivation and Context

🔒 Security

How Has This Been Tested?

I haven't checked out the code locally to verify it works. All the editing to the code was done on GitHub.com

Breaking Changes

No.

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

[Copilot]

Pull Request Overview

This PR enhances the security of Kotlin MCP server samples by changing the default host binding from 0.0.0.0 to 127.0.0.1, preventing the server from being exposed to the local network by default.

• Changed host parameter from 0.0.0.0 to 127.0.0.1 in embedded server configurations
• Applied the change to both plain configuration and Ktor plugin implementations

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[devcrocod]

relates to #232