Without proxy_ssl_server_name on, nginx connects to Cloudflare's IP
without SNI, triggering handshake_failure (alert 40). Cloudflare requires
SNI to route TLS to the correct origin.
act_runner cannot inject custom HTTP headers, so CF Access blocks its
unauthenticated calls to git.neuralplatform.ai. Add a gitea-proxy
deployment (nginx:alpine) in the ci namespace that injects the CF
Access service-token headers and proxies to https://git.neuralplatform.ai.
Both runner secrets now point GITEA_INSTANCE_URL at the in-cluster proxy
(http://gitea-proxy.ci.svc.cluster.local:3000). Build containers still
clone via SSH through git-ssh-init.sh — unaffected.