Add comprehensive internal developer platform tools guide

This extensive guide covers the most effective internal developer platform tools for 2025, providing detailed analysis of leading IDP solutions including Pulumi IDP, Backstage, Port, Humanitec, OpsLevel, Crossplane, and Kratix.

Key features:
- Comprehensive comparison of 7 major IDP tools
- Implementation strategies and best practices
- Success measurement metrics and KPIs
- Future trends in platform engineering
- Educational content positioning Pulumi IDP effectively

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: asafashirov