Bring back remap!

Partial undo of 91507f173d

hosts/mars/home.nix

@@ -36,4 +36,27 @@
   # https://nest.pijul.com/yonkeltron/macOS-nix-config:main/ZLDSMIXK5XFW6.EIAAA
   # and
   # https://github.com/bgub/nix-macos-starter/tree/main
+
+  launchd.agents.keyboard-remap = {
+    # Remap top-left key (paragraph) to backquote and backslash like
+    # proper ISO keyboard does, and the key right to the LShift to
+    # Shift.
+    enable = true;
+    config = {
+      Label = "com.user.keyboard-remap";
+      ProgramArguments = [
+        "/usr/bin/hidutil"
+        "property"
+        "--set"
+        ''
+          {"UserKeyMapping":
+            [
+              {"HIDKeyboardModifierMappingSrc":0x700000035, "HIDKeyboardModifierMappingDst":0x7000000e1},
+              {"HIDKeyboardModifierMappingSrc":0x700000064, "HIDKeyboardModifierMappingDst":0x700000035},
+            ]
+          }''
+      ];
+      RunAtLoad = true;
+    };
+  };
 }