feat(portal-shell): implement portal-shell with apollo-router integration

M8: portal-shell unified frontend shell (Modular Monolith + micro-kernel).

- Apollo Client -> apollo-router (port 4010, RSC prefetch)

- 5 layouts: classic/focus/split/triple/canvas

- Registry + PluginLoader (dynamic import ssr:false)

- 3-layer props merge, Zustand PluginStore

- 4 widgets: grades/notification-bell/user-menu/class-selector

- config-service: new pluginConfig GraphQL resolver

- apollo-router: CORS + header propagation for portal-shell

- docker-compose.yml: portal-shell service block

apps/portal-shell/next-env.d.ts

@@ -0,0 +1,5 @@
+/// <reference types="next" />
+/// <reference types="next/image-types/global" />
+
+// NOTE: This file should not be edited
+// see https://nextjs.org/docs/basic-features/typescript for more information.