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/vitest.config.ts

@@ -0,0 +1,18 @@
+import { defineConfig } from "vitest/config";
+import react from "@vitejs/plugin-react";
+import { resolve } from "node:path";
+
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    environment: "jsdom",
+    globals: true,
+    setupFiles: [],
+    include: ["src/**/*.{test,spec}.{ts,tsx}"],
+  },
+  resolve: {
+    alias: {
+      "@": resolve(__dirname, "./src"),
+    },
+  },
+});