Rework of x-os module / core profile

* move core settings to x-os
* add option to only install a lite core
* rename x-os module to core
* remove core profile from flake.nix

+  ];
+
+  options.pub-solar.core = {
+    lite-core-active = mkOption {

+    lite-core-active = mkOption {
+      description = ''
+        Whether the node should run as a server or agent.
+        Note that the server, by default, also runs as an agent.

+  pub-solar.terminal-life.enable = lib.mkIf (!cfg.lite-core-active) true;
+  pub-solar.audio.enable = lib.mkIf (!cfg.lite-core-active) true;
+  pub-solar.crypto.enable = lib.mkIf (!cfg.lite-core-active) true;
+  pub-solar.devops.enable = lib.mkIf (!cfg.lite-core-active) true;

+      # Modern modern utilities
+      p7zip
+      croc
+      jq

     pub-solar.graphical.wayland.software-renderer.enable = true;
     pub-solar.sway.terminal = "foot";
-    pub-solar.x-os.iso-options.enable = true;
+    pub-solar.core.iso-options.enable = true;