Complete migration of home-manager modules to roles

Migrate all remaining home-manager modules from home/modules/ to home/roles/
to establish a unified role-based configuration pattern. This completes the
migration started in Phase 1.

Changes:
- Phase 1-3: Migrated tmux, plasma-manager, kubectl, and emacs to roles
- Phase 4: Migrated aerospace with custom options under home.roles.aerospace.*
- Phase 5: Migrated i3+sway with shared config and override options
- Phase 6: Removed empty home/modules/ directory

All home configs now import only ./roles with role-based enable options.
Updated flake.nix machine-specific overrides to use new namespaces.

Verified with nix flake check - all configurations build successfully.

home/home-desktop.nix

@@ -17,6 +17,10 @@
     sync.enable = true;
     kdeconnect.enable = true;
     kubectl.enable = true;
+    tmux.enable = true;
+    plasma-manager.enable = true;
+    emacs.enable = true;
+    i3_sway.enable = true;
   };
 
   targets.genericLinux.enable = true;
@@ -25,10 +29,5 @@
 
   imports = [
     ./roles
-    ./modules/emacs
-    ./modules/i3+sway
-    ./modules/kubectl
-    ./modules/plasma-manager
-    ./modules/tmux
   ];
 }