[Monster12138]

Summary

This PR brings the release branch up to Familiar v3.0.1, including the changes accumulated since the current main branch:

• Add the Sprite Pack workshop for creating, editing, importing, and exporting desktop pet packs.
• Add optional fullscreen auto-hide on macOS and Windows, with non-activating restoration so returning from fullscreen preserves the active app's input focus. The setting defaults off and is hidden on Linux.
• Update bilingual README and release documentation, and bump workspace and app metadata to 3.0.1.

The v3.0.1 tag has already been pushed and its GitHub Release is published.

Validation

• cargo test --workspace
• cargo clippy --workspace --all-targets -- -D warnings
• cd app && npm run build
• The v3.0.1 release workflow completed successfully for all platform artifacts and generated SHA256SUMS.