Reuse native macOS Git credentials

docs/secure-secret-storage.md

@@ -29,7 +29,10 @@ The platform-selection code is isolated in
 
 - macOS uses legacy Keychain for command-line-compatible device-unlocked
   credentials and Protected Data for `RequireUserPresence`; iOS uses Protected
-  Data. User cancellation is mapped from the native Security Framework status.
+  Data. macOS HTTPS synchronization uses only the unique standard
+  Internet-password credential matching the remote endpoint; it does not use
+  an IronStorage-specific Git credential locator. User cancellation is mapped
+  from the native Security Framework status.
 - Windows uses Credential Manager. Store operations are serialized because the
   upstream adapter documents unreliable same-entry sequencing across threads.
 - Linux uses Secret Service through zbus with the Rust cryptography feature. It