fix(deploy): take the Gitea address for Android updates from git remote

The server kept the git.example.lan placeholder from .env.example, so the
/android page and in-app updates had no release. install.sh and update.sh now
fill GITEA_URL and GITEA_REPO from the clone's origin (https, ssh and scp
forms, credentials stripped) when they are empty or still the placeholder,
and the API treats the placeholder as not configured.

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

services/api/internal/appupdate/appupdate.go

@@ -100,8 +100,10 @@ func NewHandler(cfg Config, log *slog.Logger) *Handler {
 	return &Handler{cfg: cfg, client: &http.Client{Timeout: 10 * time.Minute}, log: log}
 }
 
+// configured — адрес и репозиторий заданы, и это не заглушка из .env.example.
 func (h *Handler) configured() bool {
-	return h.cfg.GiteaURL != "" && h.cfg.Repo != ""
+	return h.cfg.GiteaURL != "" && h.cfg.Repo != "" &&
+		!strings.Contains(h.cfg.GiteaURL, "example.") && !strings.HasPrefix(h.cfg.Repo, "owner/")
 }
 
 func (h *Handler) get(ctx context.Context, url string) (*http.Response, error) {