feat: add flake-based NixOS and Home Manager config

Co-authored-by: aider (openrouter/openai/gpt-5.2) <aider@aider.chat>

home/sam/home.nix

@@ -0,0 +1,99 @@
+{ config, pkgs, ... }:
+
+{
+  home.stateVersion = "24.05";
+
+  programs.home-manager.enable = true;
+
+  # ---
+  # Shell (zsh + oh-my-zsh + powerlevel10k)
+  # ---
+  programs.zsh = {
+    enable = true;
+    enableAutosuggestions = true;
+    enableSyntaxHighlighting = true;
+
+    oh-my-zsh = {
+      enable = true;
+      theme = "powerlevel10k/powerlevel10k";
+      plugins = [ "git" ];
+    };
+
+    shellAliases = {
+      ls = "eza --icons --git";
+      ll = "eza -l --icons --git";
+      la = "eza -la --icons --git";
+      tree = "eza --tree";
+      cat = "bat --color=always --paging=never";
+    };
+  };
+
+  programs.powerlevel10k = {
+    enable = true;
+    # Optional: link your p10k config once you add it to the repo
+    # home.file.".p10k.zsh".source = ./p10k.zsh;
+  };
+
+  # ---
+  # Shell tools
+  # ---
+  programs.atuin = {
+    enable = true;
+    enableZshIntegration = true;
+  };
+
+  programs.fzf = {
+    enable = true;
+    enableZshIntegration = true;
+  };
+
+  programs.zoxide = {
+    enable = true;
+    enableZshIntegration = true;
+  };
+
+  # ---
+  # Terminal / editor
+  # ---
+  programs.kitty.enable = true;
+
+  programs.neovim = {
+    enable = true;
+    defaultEditor = true;
+  };
+
+  # ---
+  # Packages (NOW list + a few safe essentials)
+  # ---
+  home.packages = with pkgs; [
+    git
+    curl
+    wget
+
+    eza
+    bat
+    ripgrep
+    fd
+
+    btop
+    lazygit
+    zellij
+    tealdeer
+    navi
+    yazi
+    dua
+    jq
+
+    unzip
+    zip
+    p7zip
+  ];
+
+  # ---
+  # Secrets policy
+  # ---
+  # Do NOT put API keys here (or anywhere in git).
+  # Preferred approach (local-only):
+  #   ~/.config/environment.d/10-secrets.conf
+  # or add sops-nix later.
+}