add weekly ELO rank sync from stat-check.com

- scripts/sync-elo.py: downloads Excel sheet, auto-detects columns,
  writes public/elo-data.json keyed by lowercase player name
- .gitlab-ci.yml: sync-elo stage (schedules only) commits the JSON
  then a normal push pipeline handles build + deploy; build/deploy
  skip on scheduled runs to avoid double deployment
- index.html + main.js: ELO Rank column with sort support; loads
  elo-data.json asynchronously and re-renders when ready; fails
  silently if data is missing

Requires one-time setup:
  1. GitLab project token (write_repository) stored as GITLAB_PUSH_TOKEN
  2. Pipeline schedule: cron 0 2 * * 3 (Wednesday 02:00 UTC) on main

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

index.html

@@ -76,6 +76,7 @@
               <th class="text-right hidden sm:table-cell cursor-pointer select-none" data-sort="wlt">W–L–T</th>
               <th class="text-right hidden sm:table-cell cursor-pointer select-none" data-sort="wpct">Win %</th>
               <th class="text-right hidden sm:table-cell cursor-pointer select-none" data-sort="rank">ITC Rank</th>
+              <th class="text-right hidden sm:table-cell cursor-pointer select-none" data-sort="elo">ELO Rank</th>
             </tr>
           </thead>
           <tbody id="rows"></tbody>