feat(nix): add HALO system configuration and user setup

- Added system configuration for the HALO machine, including hardware, sound, and remapping settings.
- Configured user-specific settings like session paths, favorite apps, and terminal customization.
- Introduced zram swap, SSD TRIM, and PipeWire priority tuning for performance optimization.

systems/x86_64-linux/halo/xremap.nix

@@ -0,0 +1,21 @@
+{ ... }:
+{
+  metacfg.services.xremap = {
+    enable = true;
+    deviceNames = [
+      "Hangsheng MonsGeek Keyboard"
+      "HS Galaxy100 Keyboard"
+    ];
+    config = {
+      keymap = [
+        {
+          remap = {
+            LeftAlt-C = "COPY";
+            LeftAlt-V = "PASTE";
+            LeftAlt-X = "CUT";
+          };
+        }
+      ];
+    };
+  };
+}