feat: Added shell completions directly to the nix package

flake.nix

@@ -117,7 +117,19 @@
           };
 
         packages = rec {
-          ddcbacklight = craneLib.buildPackage (commonArgs // {inherit cargoArtifacts;});
+          ddcbacklight = craneLib.buildPackage (commonArgs
+            // {inherit cargoArtifacts;}
+            // {
+              postInstall = ''
+                mkdir -p $out/bin
+                mkdir -p $out/share/bash-completions
+                mkdir -p $out/share/fish/vendor_completions.d
+                mkdir -p $out/share/zsh/site-functions
+                $out/bin/xbacklight completions bash > $out/share/bash-completions/xbacklight.bash
+                $out/bin/xbacklight completions fish > $out/share/fish/vendor_completions.d/xbacklight.fish
+                $out/bin/xbacklight completions zsh > $out/share/zsh/site-functions/_xbacklight
+              '';
+            });
           default = ddcbacklight;
         };