Added new chapters:
- Chapter 11.2: ABAP Background Processing Frameworks Evolution
- Chapter 13: Performance Tuning - The Art of ABAP Optimization

Updated build scripts to include new chapters in both PDF builds.
Successfully built PDF releases in A4 (23MB) and A5 (23MB) formats.

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

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