Admin Dashboard Graph Remake

Updated file:
- admin/dashboard.php

What changed:
1. Restarted the Admin dashboard graph area from scratch.
2. Added CSR-manager-style overview sections:
   - Overall Total
   - Today Total
3. Overview cards now show:
   - Total Requests
   - New Requests
   - Assigned
   - In Progress
   - Completed
   - Cancelled
4. Rebuilt graph section to focus only on:
   - Status Summary
   - Urgency Distribution
   - Top CX Cities by Region
   - CSR Team Performance
   - Top Appliances
   - Top Brands
5. Removed old dashboard graph sections from the visible Admin dashboard:
   - old trend chart
   - top service locations
   - peak hours
6. Top city graph is focused on CX/customer online tickets when ticket_source exists.
7. Team performance graph tries to collect team activity through CSR ownership columns, request_logs, csr_activity, and csr_activity_logs where available.
8. Kept the existing Yearly / Monthly / Weekly / Daily graph filter.

No database import is required for this update.
