Add initial Nix flake configuration for PC and Laptop with Home Manager support

- Create flake.nix to define NixOS configurations for PC and Laptop
- Add README.md with setup instructions and layout overview
- Implement common NixOS settings in modules/common.nix
- Configure Home Manager for user-specific settings in home/users/user/home.nix
- Set up hardware configurations for both PC and Laptop
- Enable Home Manager integration in host configurations
- Introduce Zen Browser package definition

flake.nix

@@ -0,0 +1,58 @@
+{
+  description = "Nix flake for PC and laptop with shared modules and Home Manager";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05"; # You can bump to a newer release later (e.g., nixos-24.11)
+
+    home-manager = {
+      url = "github:nix-community/home-manager/release-24.05";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = { self, nixpkgs, home-manager, ... }:
+    let
+      # Change this to your preferred login name once you clone on the machine(s)
+      user = "user";
+
+      mkFormatter = system: let pkgs = import nixpkgs { inherit system; }; in pkgs.alejandra;
+    in
+    {
+  # Two NixOS hosts. This flake targets x86_64-linux only.
+      nixosConfigurations = {
+        pc = nixpkgs.lib.nixosSystem {
+          system = "x86_64-linux";
+          specialArgs = {
+            inherit user;
+            # Only pass what host modules need from inputs to stay tidy
+            inputs = { inherit home-manager; };
+          };
+          modules = [ ./hosts/pc/configuration.nix ];
+        };
+
+        laptop = nixpkgs.lib.nixosSystem {
+          system = "x86_64-linux";
+          specialArgs = {
+            inherit user;
+            inputs = { inherit home-manager; };
+          };
+          modules = [ ./hosts/laptop/configuration.nix ];
+        };
+      };
+
+      # `nix fmt` support
+      formatter = {
+        x86_64-linux = mkFormatter "x86_64-linux";
+      };
+
+      # Expose custom packages
+      packages = {
+        x86_64-linux = let
+nixpkgs48 = nixpkgs; # alias
+          pkgs = import nixpkgs { system = "x86_64-linux"; };
+        in {
+          zen-browser = pkgs.callPackage ./packages/zen-browser.nix { inherit (pkgs) buildMozillaMach buildNpmPackage fetchFromGitHub lib fetchurl git pkg-config python3 vips runtimeShell writeScriptBin; };
+        };
+      };
+    };
+}