feat: installer fetched from the direct address sets it as the agent's own with the main one as fallback (and downloads from it); agents fall back to whichever address is not theirs; (direct) beside the connection status

internal/server/web/install.sh.tmpl

@@ -7,9 +7,10 @@
 set -eu
 
 HOST="${HOST:-{{.Host}}}"
-# The direct address (not behind a proxy like Cloudflare): the agent turns to
-# it when the main one is out of reach.
-FALLBACK_HOST="${FALLBACK_HOST:-{{.Direct}}}"
+# The server's other address (the direct one, not behind a proxy like
+# Cloudflare, or the main one when this script came from the direct one): the
+# agent turns to it when HOST is out of reach.
+FALLBACK_HOST="${FALLBACK_HOST:-{{.Fallback}}}"
 {{if .Secret}}ENROLL_SECRET="${ENROLL_SECRET:-{{.Secret}}}"
 {{end}}
 BIN_PATH="/usr/local/bin/lpagent"
@@ -123,7 +124,7 @@ bold "Скачивание агента ($ARCH) с $HOST…"
 TMP="$(mktemp)"
 if ! download "$HOST/download/agent-linux-$ARCH" "$TMP"; then
   if [ -n "$FALLBACK_HOST" ] && [ "$FALLBACK_HOST" != "$HOST" ]; then
-    bold "Основной адрес недоступен, скачивание с $FALLBACK_HOST…"
+    bold "$HOST недоступен, скачивание с $FALLBACK_HOST…"
     download "$FALLBACK_HOST/download/agent-linux-$ARCH" "$TMP"
   else
     red "Не удалось скачать агента."; exit 1