Rename crate to veil-rs and update Nix scripts

Change package name from veil_rs to veil-rs.
Update Cargo.toml and Cargo.lock accordingly.
Update cargoHash in default.nix for the renamed package.
Comment out postInstall step that renamed the binary.
Rename `args` variable to `_args` in main.rs to silence unused warning.

flake.nix

@@ -48,9 +48,9 @@
         #
         nativeBuildInputs = with pkgs; [pkg-config];
 
-        postInstall = ''
-          mv $out/bin/veil_rs $out/bin/veil-rs
-        '';
+        # postInstall = ''
+        #   cp static files
+        # '';
       };
     };