fix: add pagination to get_tickets endpoint for performance with large datasets

[tmdeveloper007]

Issue Description

The get_tickets endpoint in backend/main.py returns ALL tickets with query.execute() without any pagination parameters. For companies with thousands of tickets, this causes performance issues.

Expected Fix

Add optional limit (default 50) and offset (default 0) query parameters and apply them to the Supabase query before executing.

Files to Modify

• backend/main.py (lines 1148-1165)