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>

Dockerfile

@@ -0,0 +1,22 @@
+# ── Stage 1: build ──────────────────────────────────────────────────────────
+FROM node:22-alpine AS builder
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm ci
+
+COPY . .
+# No VITE_FOOTBALL_API_KEY needed at build time — nginx handles auth
+RUN npm run build
+
+# ── Stage 2: serve ──────────────────────────────────────────────────────────
+FROM nginx:alpine
+
+# Copy built assets
+COPY --from=builder /app/dist /usr/share/nginx/html
+
+# Copy nginx template — the official nginx image runs envsubst on *.template
+# files at startup, producing /etc/nginx/conf.d/default.conf
+COPY nginx/default.conf.template /etc/nginx/templates/default.conf.template
+
+EXPOSE 80