Refactor dashboard logic from AuthService into dedicated service

[nanaf6203-bit]

Problem

AuthService.getDashboard() contains user dashboard logic with 17+ queries, duplicating patterns from AdminService.getDashboard().

Expected Outcome

Consolidated, cached, optimized dashboard service for both user and admin.

Acceptance Criteria

• Move user dashboard to dedicated DashboardService
• Consolidate duplicate query patterns
• Add missing admin metrics
• Cache dashboard responses

Files Affected

src/auth/auth.service.ts, src/dashboard/dashboard.service.ts, src/admin/admin.service.ts

Difficulty

Easy

Estimated Effort

Small (2-3 days)

Labels

refactoring, performance, dashboard

[OAKVISUALZ]

Please assign me this issue.