Improve installation logic for pacman and yay

Refactor pacman and yay installation checks and commands.

install.sh

@@ -138,10 +138,10 @@ for selection in $CHOICE; do
         "4")
             echo "Installing Pacman Packages..."
             # Check if pacman binary is installed
-            if command -v pacman >/dev/null; then
+            if ! command -v pacman >/dev/null; then
                 echo "Cannot proceed: pacman binary not found"
                 exit 1 # exit with an error
-            fi
+            else
                 # Install pacman packages
                 # Runs local script unless it does not exit or fails
                 if [[ -f "./configs/PackagesPacman.txt" ]]; then
@@ -154,14 +154,15 @@ for selection in $CHOICE; do
                     echo "--------------------------------------------------------------------"
                     echo "+ sleep 10" && sleep 10
                 fi
+            fi
             ;;
         "5")
             echo "Installing Yay and Yay Packages..."
             # Check for pacman before installing yay
-            if command -v pacman >/dev/null; then
+            if ! command -v pacman >/dev/null; then
                 echo "Cannot proceed: Not a arch based system"
                 exit 1 # Exit with an error
-            fi
+            else
                 # Install yay prerequisites
                 if ! sudo pacman -S --needed --noconfirm efibootmgr sbsigntools mokutil sbctl golang fakeroot debugedit make gcc; then
                     echo "--------------------------------------------------------------------"
@@ -203,6 +204,7 @@ for selection in $CHOICE; do
                     echo "--------------------------------------------------------------------"
                     echo "+ sleep 10" && sleep 10
                 fi
+            fi
             ;;
         *)
             echo "Invalid option selected: $selection"