fix: skip empty native save archives

[dmuiX]

Summary

Treat a mounted native save container with zero files as SAVEDATA_NO_SAVE_DATA and remove its staged archive instead of uploading it.

Why

A title can have a mountable Horizon save container before the game has written any files. ZipWriter still creates a technically valid 22-byte empty ZIP, and the previous code returned success because it only checked whether individual add() calls failed. With no files, no call fails.

That empty ZIP is non-zero-length, so transport-level empty-body checks cannot identify it. Once committed, it becomes the latest revision and restore validation must reject it.

Implementation

• count successfully archived entries under saves/;
• if the count is zero, close and remove the staged ZIP;
• return the existing SAVEDATA_NO_SAVE_DATA result;
• do not count BCAT entries because native restore requires actual save data;
• increment the bundled sysmodule version so installed services receive the fix.

Validation

Both the app and sysmodule build successfully from a clean client build. The issue was reproduced on hardware with a never-played installed title: every generated archive was exactly 22 bytes with zero ZIP entries.