docs(readme): redesign README with architecture-first engineering documentation

* completely rewrote README structure and presentation
* added flagship ASCII project branding
* introduced architecture-first documentation style
* added Mermaid diagrams for workflow, trust boundaries, and validator network
* redesigned feature presentation using capability tables
* added stakeholder-oriented system explanation
* improved contributor section with profile cards and role visualization
* enhanced academic guidance section with structured acknowledgements
* added engineering principles and deployment posture sections
* improved visual hierarchy using NOTE / TIP / WARNING / IMPORTANT blocks
* refined blockchain, verification, and security explanations
* improved overall readability, scannability, and recruiter-facing presentation
* aligned repository presentation with production-grade open-source standards

Author: udaycodespace