No diagnostic when a module ships routes/views but skips register_menu_items / register_permissions

[antosubash]

Fixed in #87 (with refinements in #88) — the diagnostic now exists as SM019: a module that overrides register_routes with a non-empty view_prefix but registers neither menu items nor permissions emits a warning at boot. Per #88, registering permissions alone is sufficient (sub-pages reachable via the role editor without a sidebar entry). See framework/core/simple_module_core/diagnostics/_module.py:130-159 and CLAUDE.md's diagnostic codes table.