docs: create comprehensive CHANGELOG.md and update documentation

- Created complete CHANGELOG.md from v1.0.0 to v2.7.0 based on git history
- Updated README.md to fix incorrect CHANGELOG path reference
- Added n8n-docs/ directory to .gitignore (was accidentally tracked)
- Removed n8n-docs from git tracking

The CHANGELOG now follows Keep a Changelog format and includes all major features,
fixes, and improvements for each version with proper categorization.

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

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

README.md

@@ -529,62 +529,6 @@ Current database coverage (n8n v1.99.1):
 - ✅ **ENHANCED**: Error messages with clear guidance and examples
 - ✅ **PREVENTS**: Broken workflows that show as question marks in n8n UI
 
-### v2.6.1 - Enhanced typeVersion Validation
-- ✅ **NEW**: typeVersion validation for all versioned nodes
-- ✅ **CATCHES**: Missing typeVersion with correct version suggestions
-- ✅ **WARNS**: Outdated node versions in use
-- ✅ **PREVENTS**: Invalid versions that exceed maximum supported
-- ✅ **HELPS**: AI agents avoid common workflow creation mistakes
-
-### v2.6.0 - n8n Management Tools Integration
-- ✅ **NEW**: 14 n8n management tools for complete workflow lifecycle
-- ✅ **NEW**: Create, update, execute workflows via API
-- ✅ **NEW**: Webhook workflow triggering support
-- ✅ **NEW**: Execution monitoring and management
-- ✅ **INTEGRATED**: n8n-manager-for-ai-agents functionality
-- ✅ **OPTIONAL**: Only enabled when N8N_API_URL and N8N_API_KEY configured
-
-### v2.5.1 - AI Tool Support Enhancement
-- ✅ **NEW**: AI tool connection validation in workflows
-- ✅ **NEW**: `get_node_as_tool_info` - Guidance for using ANY node as AI tool
-- ✅ **ENHANCED**: `get_node_info` now includes aiToolCapabilities section
-- ✅ **IMPROVED**: Workflow validation understands ai_tool connections
-- ✅ **ADDED**: $fromAI() expression validation for dynamic AI parameters
-- ✅ **CLARIFIED**: ANY node can be used as an AI tool, not just usableAsTool nodes
-
-### v2.5.0 - Complete Workflow Validation
-- ✅ **NEW**: `validate_workflow` - Validate entire workflows before deployment
-- ✅ **NEW**: `validate_workflow_connections` - Check workflow structure
-- ✅ **NEW**: `validate_workflow_expressions` - Validate n8n expressions
-- ✅ **NEW**: Cycle detection for workflows
-- ✅ **NEW**: Expression syntax validation
-
-### v2.4.2 - Professional Validation System
-- ✅ **NEW**: `validate_node_operation` - Operation-aware validation with 80% fewer false positives
-- ✅ **NEW**: `validate_node_minimal` - Lightning-fast required field checking
-- ✅ **NEW**: Validation profiles - Choose between minimal, runtime, ai-friendly, or strict
-- ✅ **NEW**: Node validators for Webhook, Postgres, MySQL with SQL safety checks
-- ✅ **IMPROVED**: Deduplicates errors, filters internal properties
-- ✅ **ADDED**: Basic code syntax validation for JavaScript/Python
-- ✅ **ADDED**: SQL injection detection and unsafe query warnings
-- ✅ **FIXED**: Removed deprecated `validate_node_config` tool
-
-### v2.4.0 - AI-Optimized Tools & MIT License
-- ✅ **NEW**: `get_node_essentials` - 95% smaller responses
-- ✅ **NEW**: Task templates for common automations
-- ✅ **NEW**: Configuration validation
-- ✅ Fixed missing AI/LangChain documentation
-- ✅ Changed to MIT License for wider adoption
-
-### v2.3.3 - Automated Updates
-- ✅ Weekly automated n8n dependency updates
-- ✅ GitHub Actions workflow
-- ✅ AI-capable nodes: 35 → 263
-
-### v2.3.0 - Universal Compatibility
-- ✅ Works with ANY Node.js version
-- ✅ Automatic database adapter fallback
-- ✅ No manual configuration needed
 
 See [CHANGELOG.md](./docs/CHANGELOG.md) for full version history.