chore: upgrade from nix-shell to nix flake

flake.nix

@@ -0,0 +1,44 @@
+{
+  description = "A Nix flake for the meshStack docs developer shell";
+
+  inputs = {
+    nixpkgs.url = "nixpkgs/nixos-24.11";
+    flake-utils.url = "github:numtide/flake-utils";
+
+    # Fixing packages
+    # 1. Find out which package is needed under https://search.nixos.org/packages
+    # 2. Search package under https://lazamar.co.uk/nix-versions/ and pick version
+    # 3. Extract the packages as per instructions
+    # 4. Add packages in pkgs.mkShell
+    dhall-pkgs = {
+      url = "github:NixOS/nixpkgs/d86bcbb415938888e7f606d55c52689aec127f43";
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, dhall-pkgs }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+        dhallpkgs = import dhall-pkgs { inherit system; };
+
+        fix_dhall = dhallpkgs.haskellPackages.dhall_1_41_1; # https://lazamar.co.uk/nix-versions/?channel=nixpkgs-unstable&package=dhall
+        fix_dhall_docs = dhallpkgs.haskellPackages.dhall-docs; # https://lazamar.co.uk/nix-versions/?channel=nixpkgs-unstable&package=dhall-docs
+        fix_dhall_json = dhallpkgs.haskellPackages.dhall-json_1_7_10; # https://lazamar.co.uk/nix-versions/?channel=nixpkgs-unstable&package=dhall-json
+        fix_dhall_lsp = dhallpkgs.dhall-lsp-server;
+
+        core_packages = [
+          # node / typescript (meshPanel, utilities eetc.)
+          pkgs.nodejs_22
+          (pkgs.yarn.override {
+            nodejs = pkgs.nodejs_22;
+          })
+        ];
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          name = "shell with all basic runtimes and tools";
+          packages = core_packages;
+        };
+      }
+    );
+}