Add Docker + nginx deployment for homelab

- Multi-stage Dockerfile: Node builds static assets, nginx serves them
- nginx proxies /api/* to football-data.org and injects X-Auth-Token
  server-side via FOOTBALL_API_KEY env var (key never in browser bundle)
- docker-compose.yml exposes the app on port 3000
- Extract apiFetch() helper: sends key in dev (Vite proxy), skips in prod
- .env.example updated with both dev and production key vars

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

nginx/default.conf.template

@@ -0,0 +1,20 @@
+server {
+    listen 80;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # Proxy /api/* → football-data.org, injecting the API key server-side
+    location /api/ {
+        proxy_pass         https://api.football-data.org/v4/;
+        proxy_set_header   Host api.football-data.org;
+        proxy_set_header   X-Auth-Token ${FOOTBALL_API_KEY};
+        proxy_ssl_server_name on;
+        proxy_hide_header  Access-Control-Allow-Origin;
+        add_header         Access-Control-Allow-Origin $http_origin always;
+    }
+
+    # SPA fallback: all unmatched routes serve index.html
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+}