Configure env variables for Gitea Actions build step

Add secrets to build step in deploy.yaml:
- NEXT_PUBLIC_API_BASE
- SERVER_ID
- ACCESS_TOKEN

These are baked into static export during build, not needed by Cloudflare.

.gitea/workflows/deploy.yaml

@@ -18,6 +18,10 @@ jobs:
 
       - name: Build
         run: npm run build
+        env:
+          NEXT_PUBLIC_API_BASE: ${{ secrets.NEXT_PUBLIC_API_BASE }}
+          SERVER_ID: ${{ secrets.SERVER_ID }}
+          ACCESS_TOKEN: ${{ secrets.ACCESS_TOKEN }}
 
       - name: Publish to Cloudflare
         uses: cloudflare/wrangler-action@v3