feat(ci-reports): publish report.tar.gz archive for offline download

Pack HTML report after publish; link archive in run index and CI log.
Add fetch-ci-report.sh helper for agent curl/extract.

[skip ci]

docker/ci-reports/nginx.conf

@@ -5,6 +5,13 @@ server {
     autoindex on;
     charset utf-8;
 
+    # Archives for curl/agent offline analysis (before Allure SPA fallback)
+    location ~* \.(tar\.gz|tgz|zip)$ {
+        default_type application/gzip;
+        add_header Content-Disposition 'attachment';
+        try_files $uri =404;
+    }
+
     location / {
         try_files $uri $uri/ =404;
     }