feat: database-first refactor, unified architecture and visual developer manual

Summary of changes:
- Consolidated Studio+CMS and Experience+LMS into unified services.
- Moved core business logic (enrollment, grading, auth) to PostgreSQL functions.
- Implemented advanced auditing via DB triggers and session context.
- Added gamification (XP/Levels/Leaderboards) and logic encapsulation.
- Updated installation/diagnostic scripts for the new architecture.
- Created a comprehensive Visual Developer Manual in README.md with hardware scaling.

services/cms-service/Cargo.toml

@@ -20,3 +20,6 @@ tower-http.workspace = true
 reqwest.workspace = true
 bcrypt.workspace = true
 jsonwebtoken.workspace = true
+hmac.workspace = true
+sha2.workspace = true
+hex.workspace = true