Extract aerospace configuration into reusable modules

Create both home-manager and nix-darwin modules for aerospace window
manager configuration, removing 110+ lines of duplicated config from
machine-specific files.

Changes:
- Add home/modules/aerospace module with configurable leader key
- Add modules/aerospace.nix for system-level macOS settings
- Include autoraise configuration in home module
- Update home-darwin-work.nix to use new modules
- Update johno-macbookpro configuration to use system module
- Remove inline aerospace/autoraise config and launchd agents

modules/aerospace.nix

@@ -0,0 +1,30 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.aerospace;
+in
+{
+  options.services.aerospace = {
+    enable = mkEnableOption "AeroSpace window manager system configuration";
+
+    enableSpansDisplays = mkOption {
+      type = types.bool;
+      default = true;
+      description = ''
+        Configure macOS Spaces to span displays (required for aerospace multi-monitor support).
+        When enabled, sets com.apple.spaces.spans-displays to true.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    # Configure spaces to span displays (required for aerospace multi-monitor support)
+    system.defaults.CustomUserPreferences = mkIf cfg.enableSpansDisplays {
+      "com.apple.spaces" = {
+        spans-displays = true;
+      };
+    };
+  };
+}