Add options for built-in SSH server and HTTP bind address

- gitea_ssh_builtin: use Gitea's built-in SSH server (default false)
- gitea_ssh_listen_port: SSH listen port, falls back to ssh_port
- gitea_http_addr: optional HTTP bind address
- grant CAP_NET_BIND_SERVICE when the built-in server uses a port < 1024

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

defaults/main.yml

@@ -23,6 +23,8 @@ gitea_domain: localhost
 gitea_domain_protocol: https
 gitea_port: 3000
 gitea_ssh_domain: localhost
+# use Gitea's built-in SSH server instead of the system sshd
+gitea_ssh_builtin: false
 
 gitea_internal_token: INTERNAL_TOKEN
 gitea_jwt_secret: JWT_SECRET