ci: point Docker registry at internal Gitea (10.5.0.195:3000)

Cut the dependency on the public hostname gitea.danielarroyo.cl and
push straight to the LAN Gitea instance. Internal Gitea is plain HTTP,
so the docker daemon on the LXC needs 'insecure-registries' set, and
the gitea-runner-lxc has to be re-registered against the new URL
(separate manual steps; not in this repo).

- ci.yml: docker login, both docker tag, both push_with_retry, and
  docker logout now target 10.5.0.195:3000
- compose.yaml: image URL switched to 10.5.0.195:3000

The CI workflow itself, the Dockerfile, and the build command are
unchanged - only the registry target moved.

compose.yaml

@@ -1,6 +1,6 @@
 services:
   shot-crafter:
-    image: gitea.danielarroyo.cl/proyectos/shot-crafter-calculator:latest
+    image: 10.5.0.195:3000/proyectos/shot-crafter-calculator:latest
     container_name: shot-crafter
     restart: unless-stopped
     ports: