flake: init and rename php files

.gitignore

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+tags

flake.nix

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+{
+  description = "b12f invoiceplane template";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-23.11";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+  };
+
+  outputs = inputs@{ self, ... }:
+    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
+      perSystem = args@{ system, pkgs, lib, config, ... }: let
+        invoiceplane-template = pkgs.stdenv.mkDerivation {
+          name = "invoiceplane-template";
+          src = ./.;
+          installPhase = '' 
+            mkdir -p $out
+            cp *.php $out/
+          '';
+        };
+      in {
+        packages.default = invoiceplane-template;
+        packages.invoiceplane-template = invoiceplane-template;
+      };
+    };
+}