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/migrations/20260111000000_gamification_users.sql

@@ -0,0 +1,4 @@
+-- Add XP and Level to users for gamification
+ALTER TABLE users
+ADD COLUMN xp INTEGER NOT NULL DEFAULT 0,
+ADD COLUMN level INTEGER NOT NULL DEFAULT 1;