iOS: keep older build numbers when regenerating the source

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

ios/source.json

@@ -26,7 +26,7 @@
         },
         {
           "version": "1.0.3",
-          "buildVersion": "1.0.3",
+          "buildVersion": "4",
           "date": "2026-10-20T09:08:18-07:00",
           "localizedDescription": "Bundle ID is now org.cdnutter.stemify (delete the old app first; settings won't carry over). IPA is named stemify-<version>.ipa. Adds an AltStore/SideStore/Feather source.",
           "downloadURL": "https://git.iamchrisama.com/cdnutter/stemify/releases/download/ios-v1.0.3/stemify-1.0.3.ipa",