feat: Add Web MCP tutorial

[meirk-brd]

Motivation and Context

This PR adds a new example demonstrating how to integrate Koog AI agents with Bright Data's Web MCP server for AI-driven web scraping and data collection. The example shows how to:

• Connect to external MCP servers via STDIO transport
• Configure environment variables for API tokens
• Create AI agents with web scraping capabilities
• Perform natural language-driven data collection tasks

This addresses the need for practical examples of MCP integration with third-party services, particularly for web scraping use cases that are common in AI agent workflows.

Breaking Changes

No breaking changes. This is a new example that doesn't modify existing APIs or functionality.

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Type of the changes

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

Checklist

• [x] The pull request has a description of the proposed change
• [x] I read the [Contributing Guidelines](https://github.com/JetBrains/koog/blob/main/CONTRIBUTING.md) before opening the pull request
• [x] The pull request uses develop as the base branch
• [ ] Tests for the changes have been added
• [ ] All new and existing tests passed

Additional steps for pull requests adding a new feature

• [ ] An issue describing the proposed change exists
• [ ] The pull request includes a link to the issue
• [ ] The change was discussed and approved in the issue
• [x] Docs have been added / updated