feat: initial m3ta-home structure

- flake.nix with nixpkgs, home-manager, nix-colors, m3ta-nixpkgs, agenix, NUR inputs
- lib/mkHome.nix: compose HM config from user + identity + context + sets
- profiles/base: shell, cli-tools, secrets (always loaded)
- profiles/contexts/desktop: WM, apps, theme, ghostty
- profiles/contexts/server: minimal headless
- profiles/sets/coding: core (git, direnv, jq, rg), editor, lsp, languages, agents
- profiles/sets/gaming: steam, gamescope, gpu
- profiles/sets/media: obs, ffmpeg, kdenlive, handbrake, yt-dlp
- users/m3tam3re/identities: private.nix, work.nix (git, jj, ssh per identity)
- users/m3tam3re/preferences: cliphist, difftastic, base packages

profiles/base/cli-tools/zellij.nix

@@ -0,0 +1,34 @@
+# Zellij terminal multiplexer with nix-colors theming.
+{
+  config,
+  lib,
+  ...
+}:
+with lib; let
+  cfg = config.base.cliTools.zellij;
+in {
+  # Enabled by default — base modules are always-on.
+  options.base.cliTools.zellij.enable = (mkEnableOption "enable zellij multiplexer") // {default = true;};
+
+  config = mkIf cfg.enable {
+    programs.zellij = {
+      enable = true;
+      settings = {
+        theme = "universal";
+        themes.universal = {
+          bg = "#${config.colorScheme.palette.base00}";
+          fg = "#${config.colorScheme.palette.base05}";
+          black = "#${config.colorScheme.palette.base01}";
+          red = "#${config.colorScheme.palette.base08}";
+          green = "#${config.colorScheme.palette.base0B}";
+          yellow = "#${config.colorScheme.palette.base0A}";
+          blue = "#${config.colorScheme.palette.base0D}";
+          magenta = "#${config.colorScheme.palette.base0E}";
+          cyan = "#${config.colorScheme.palette.base0C}";
+          white = "#${config.colorScheme.palette.base07}";
+          orange = "#${config.colorScheme.palette.base09}";
+        };
+      };
+    };
+  };
+}