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>

.gitlab-ci.yml

@@ -1,7 +1,26 @@
 stages:
+  - sync
   - build
   - deploy
 
+# Runs only on scheduled pipelines (every Wednesday via GitLab schedule).
+# Downloads the stat-check.com ELO Excel sheet, writes public/elo-data.json,
+# then commits and pushes so a normal build+deploy pipeline picks it up.
+# Requires CI variable: GITLAB_PUSH_TOKEN (project token, write_repository scope)
+sync-elo:
+  stage: sync
+  only:
+    - schedules
+  script:
+    - python3 scripts/sync-elo.py
+    - git config user.email "ci@gateway-gamers.net"
+    - git config user.name "GG CI Bot"
+    - git remote set-url origin "https://oauth2:${GITLAB_PUSH_TOKEN}@gl.mando.club/mandalore/40k-rankings.gateway-gamers.net.git"
+    - git add public/elo-data.json
+    - git diff --staged --quiet && echo "No ELO changes." || (git commit -m "sync: update ELO data" && git push origin HEAD:main)
+
+# Build and deploy skip on scheduled pipelines — the robot push above
+# triggers its own normal pipeline that handles the actual build + deploy.
 build:
   stage: build
   script:
@@ -13,6 +32,8 @@ build:
     expire_in: 1 hour
   only:
     - main
+  except:
+    - schedules
 
 deploy:
   stage: deploy
@@ -20,6 +41,8 @@ deploy:
     - rsync -avz --delete dist/ /var/www/domains/gateway-gamers.net/40k-rankings/
   only:
     - main
+  except:
+    - schedules
   environment:
     name: production
     url: https://40k-rankings.gateway-gamers.net