docs: update README and documentation to match current state (v2.5.1)

- Update n8n version from v1.97.1 to v1.99.1 in README
- Fix 7 broken documentation links to point to existing files
- Standardize Docker image size to ~280MB across all docs (was inconsistent: 150MB/200MB/283MB)
- Add missing npm scripts for test commands (test:essentials, test:enhanced-validation, etc.)
- Update CHANGELOG.md with missing versions 2.4.0 through 2.5.1
- Update README_CLAUDE_SETUP.md to list all 21+ MCP tools (was only showing 6)
- Document 5 additional npm scripts in CLAUDE.md
- Update AI-capable nodes count to 263 (was 35 in old docs)

All documentation now accurately reflects the current codebase state.

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

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

scripts/build-optimized.sh

@@ -42,8 +42,8 @@ docker run --rm n8n-mcp:latest node -e "console.log('Build OK - Runtime dependen
 echo ""
 echo "💰 Size comparison:"
 echo "   Old approach (with n8n deps): ~1.5GB"
-echo "   New approach (runtime only):  ~200MB"
-echo "   Savings: ~87% smaller!"
+echo "   New approach (runtime only):  ~280MB"
+echo "   Savings: ~82% smaller!"
 
 echo ""
 echo "✅ Build complete!"