Lumiere v2.5.3 - GHL Appointment Import Fix

Changes:
- Backfill stops at the current UTC date; it no longer scans one year into the future.
- Queries GHL events by both calendarId and userId, then de-duplicates by event ID.
  This helps recover appointments attached to older calendar IDs while retaining current-calendar coverage.
- Keeps bounded 30-day API windows and automatic timeout splitting.
- Existing appointment rows are UPSERTed by GHL event ID.
- Pagination navigation arrows are visually centered in their buttons.

Run:
1. /lumiere/import/install_schema.php
2. /lumiere/import/import_ghl_appointments.php

Ongoing cron:
/lumiere/import/import_ghl_appointments.php?mode=recent
