docs: deprecate docs/advanced folder

- Removed docs/advanced/README.md (minimal placeholder content)
- Topics already covered in other documentation files:
  - Advanced blockchain operations -> docs/blockchain/
  - Multi-chain architecture -> docs/blockchain/cross-chain/
  - Cross-node communication -> docs/agents/
  - Advanced agent specialization -> docs/agents/
  - Performance optimization -> docs/architecture/
  - Security best practices -> docs/security/
- Updated DOCUMENTATION_CLEANUP_SUMMARY.md to note deprecation
- No content merge needed as README was just a placeholder

docs/advanced/README.md

@@ -1,32 +0,0 @@
-# Advanced AITBC Documentation
-
-This section contains advanced documentation for experienced AITBC users and developers.
-
-## Contents
-
-- Advanced blockchain operations
-- Multi-chain architecture
-- Cross-node communication
-- Advanced agent specialization
-- Performance optimization
-- Security best practices
-
-## Prerequisites
-
-Before reading advanced documentation, ensure you have:
-- Completed the foundation training stages
-- Familiarity with basic AITBC CLI commands
-- Understanding of blockchain concepts
-- Experience with Python development
-
-## Related Resources
-
-- [Training Stages](../agent-training/README.md)
-- [Operations Audit](../agent-training/OPERATIONS_AUDIT.md)
-- [CLI Documentation](../cli/README.md)
-
-## Quality Metrics
-
-- Documentation completeness: 100%
-- Code examples: Included
-- Validation: Automated

docs/archive/summaries/DOCUMENTATION_CLEANUP_SUMMARY.md

@@ -173,7 +173,7 @@ expert/
 ### **Updated Paths**:
 - `/docs/0_getting_started/` → `/docs/beginner/01_getting_started/`
 - `/docs/10_plan/` → `/docs/intermediate/01_planning/`
-- `/docs/6_architecture/` → `/docs/advanced/03_architecture/`
+- `/docs/6_architecture/` → `/docs/advanced/03_architecture/` (docs/advanced folder deprecated May 2026)
 - `/docs/12_issues/` → `/docs/expert/01_issues/`
 
 ### **Legacy Support**: