Initialize Node.js Specialized Architectural Documentation

[beginwebdev2002]

Initialized architecture.md and security-best-practices.md within backend/nodejs enforcing strict YAML frontmatter, the 4-step structural lifecycle constraint, and incorporating Mermaid design tokens. Cleaned up redundant navigation sections in redis/readme.md and updated nodejs/readme.md linking points, abiding by the 'Zero-Approval' operational protocol for the backend directory.

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PR created automatically by Jules for task 4169199687567096715 started by @beginwebdev2002

[google-labs-jules]

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