Initial commit: GitLab repository delivery middleware

HTTP service that fetches GitLab repository archives for configured
customers, merges them into a single tarball, and returns an encrypted
payload. Includes Nix flake for reproducible builds.

flake.nix

@@ -0,0 +1,34 @@
+{
+	description = "Repo delivery middleware";
+
+	inputs = {
+		nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+	};
+
+	outputs = { self, nixpkgs }:
+		let
+			systems = [ "x86_64-linux" "aarch64-linux" ];
+			forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f {
+				pkgs = nixpkgs.legacyPackages.${system};
+			});
+		in
+		{
+			packages = forAllSystems ({ pkgs }: {
+				default = pkgs.buildGoModule {
+					pname = "repo-delivery-middleware";
+					version = "0.1.0";
+					src = ./src;
+					vendorHash = "sha256-CVycV7wxo7nOHm7qjZKfJrIkNcIApUNzN1mSIIwQN0g=";
+				};
+			});
+
+			devShells = forAllSystems ({ pkgs }: {
+				default = pkgs.mkShell {
+					packages = with pkgs; [
+						go
+						gopls
+					];
+				};
+			});
+		};
+}