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.

flake.nix

@@ -133,7 +133,7 @@
           home-manager.users.johno = {
             imports = [ ./home/home-laptop-compact.nix ];
             # Machine-specific overrides
-            home.i3_sway.extraSwayConfig = {
+            home.roles.i3_sway.extraSwayConfig = {
               output.eDP-1.scale = "1.75";
             };
           };