chore(caddy): serve the Gitea site alongside the app

The git server runs as its own stack in /opt/gitea and is reached by container
name over the app's internal network, publishing no host port of its own. Only
the reverse-proxy entry belongs here, where the Caddyfile lives.

Caddyfile

@@ -10,3 +10,9 @@
     # Backspace API, WebSocket, and frontend — Docker DNS resolves "backspace"
     reverse_proxy backspace:3000
 }
+
+# Gitea — servidor git próprio (stack em /opt/gitea). Alcançado pelo nome do
+# container na rede interna; o Gitea não publica porta nenhuma no host.
+{$GIT_DOMAIN:git.resenha.website} {
+    reverse_proxy gitea:3000
+}