docs: align README, panel-guide, and installer messages

Describe :80 landing vs :HOST_PORT admin; export filename ASCII note.
Fix install.sh echoes that still referred to a support footer on landing.

Co-authored-by: Cursor <cursoragent@cursor.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "amnezia-admin",
-  "version": "1.1.1",
+  "version": "1.1.2",
   "private": true,
   "description": "Web-панель AmneziaWG: несколько инстансов, WARP, каскад/Endpoint, экспорт .conf (Docker)",
   "license": "MIT",