[darwin] Update screengrab keys

These conflict with aerospace space-management actions

roles/darwin.nix

@@ -45,6 +45,41 @@ in
 
     time.timeZone = "America/Los_Angeles";
 
+    # System preferences
+    system.defaults = {
+      # Custom keyboard shortcuts
+      CustomUserPreferences = {
+        "com.apple.symbolichotkeys" = {
+          AppleSymbolicHotKeys = {
+            # Screenshot - Capture entire screen (Cmd+Ctrl+3)
+            "28" = {
+              enabled = true;
+              value = {
+                parameters = [ 51 20 1310720 ];
+                type = "standard";
+              };
+            };
+            # Screenshot - Capture selected portion (Cmd+Ctrl+4)
+            "30" = {
+              enabled = true;
+              value = {
+                parameters = [ 52 21 1310720 ];
+                type = "standard";
+              };
+            };
+            # Screenshot - Show screenshot toolbar (Cmd+Ctrl+5)
+            "184" = {
+              enabled = true;
+              value = {
+                parameters = [ 53 23 1310720 ];
+                type = "standard";
+              };
+            };
+          };
+        };
+      };
+    };
+
     environment.systemPackages = with pkgs; [
       git
       glances