Update Helium to 0.16.3.1 and add Cargo module

Bump Helium AppImage version and update its SHA‑256 hash.
Add a new home module that installs a .cargo/config.toml with a custom
registry and enables git‑fetch‑with‑cli.

modules/home/noctalia/default.nix

@@ -18,3 +18,4 @@
 #   programs.noctalia.settings = {
 #   };
 # }
+