Refactor Nix package definition and enhance README for lidarr-mb-gap

- Updated `flake.nix` to import the new Nix package definition from `nix/package.nix`, streamlining the build process for the lidarr-mb-gap application.
- Enhanced the README.md to include new features such as NixOS module support for automated deployment, detailed deployment instructions, and configuration options for SSH and output directories.
- Added sections for troubleshooting output file issues and clarified the structure of the project, including new files for deployment and web serving.

flake.nix

@@ -21,18 +21,9 @@
       let
         pkgs = import nixpkgs { inherit system; };
         lib = pkgs.lib;
-        lidarr-mb-gap = pkgs.python3Packages.buildPythonApplication {
-          pname = "lidarr-mb-gap";
-          version = "1.0.0";
+        lidarr-mb-gap = import ./nix/package.nix {
+          inherit pkgs lib;
           src = lib.cleanSource ./src;
-          format = "pyproject";
-          nativeBuildInputs = with pkgs.python3Packages; [
-            setuptools
-          ];
-          propagatedBuildInputs = with pkgs.python3Packages; [
-            requests
-            python-dotenv
-          ];
         };
       in
       {