feat(web): list previous app builds on the download page

GET /app/clients now returns up to 8 Gitea releases per OS so users can download older installers while they still exist after prune.

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

packages/i18n/locales/en/auth.json

@@ -40,6 +40,7 @@
     },
     "version": "version {{version}}",
     "other": "Other platforms",
+    "older": "Previous versions",
     "step_install": {
       "android": "Open the downloaded file. If Android asks, allow installs from this source.",
       "windows": "Run the installer and follow the steps. pipu will appear in the Start menu.",