feat(packages/rebuild): improve rebuild script

.gitignore

@@ -0,0 +1,2 @@
+result
+*.qcow2

packages/rebuild/default.nix

@@ -2,13 +2,32 @@
 pkgs.writeShellScriptBin "rebuild" # sh
   ''
     if [ ! -f "flake.nix" ]; then
-    echo "flake.nix not found in current directory. exiting..."
-    exit 1
+      echo "Error: flake.nix not found in the current directory. Exiting."
+      exit 1  # Indicate an error
     fi
 
-    git add . && \
-    nixos-rebuild switch --flake . --use-remote-sudo && \
-    ${pkgs.cowsay}/bin/cowsay -f elephant "Opening a test shell. Type exit 1 to abort and exit to commit your changes." && \
-    $SHELL && \
-    git commit -a
+    echo "--- building the new config... ---"
+    git add .
+    nixos-rebuild test --flake . --use-remote-sudo || {
+      echo "Error: nixos-rebuild switch failed.  Check the output for details."
+      exit 1
+    }
+
+    echo "--- diffing... ---"
+    git diff HEAD --color=always --stat --patch
+
+    echo "--- opening test shell... ---"
+    ${pkgs.cowsay}/bin/cowsay -f elephant "Entering a test shell.  Type 'exit 1' to abort changes and 'exit' to commit."
+    PS1="Test shell> " $SHELL || {
+      ${pkgs.cowsay}/bin/cowsay -f satanic "You aborted."
+      exit 1
+    }
+
+    echo "--- adding the built configuration to the bootloader... ---"
+    nixos-rebuild switch --flake . --use-remote-sudo || {
+      echo "Error: nixos-rebuild switch failed.  Check the output for details."
+      exit 1
+    }
+    git commit
+    exit 0
   ''