Refactor Nix package definitions for improved clarity and consistency, including updates to overlays, dependencies, and build inputs across multiple packages.

src/download/shell.nix

@@ -3,17 +3,16 @@
 }:
 
 pkgs.mkShell {
-  packages =
-    [
-      (pkgs.python3.withPackages (
-        ps:
-        builtins.attrValues {
-          inherit (ps) setuptools pyyaml types-pyyaml;
-        }
-      ))
-    ]
-    ++ builtins.attrValues {
-      inherit (pkgs) yt-dlp gallery-dl ffmpeg;
-    };
+  packages = [
+    (pkgs.python3.withPackages (
+      ps:
+      builtins.attrValues {
+        inherit (ps) setuptools pyyaml types-pyyaml;
+      }
+    ))
+  ]
+  ++ builtins.attrValues {
+    inherit (pkgs) yt-dlp gallery-dl ffmpeg;
+  };
   buildInputs = [ ];
 }