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/src/widgets/sidebar/class-selector/index.tsx

@@ -0,0 +1,70 @@
+"use client";
+
+/**
+ * class-selector（sidebar / side）
+ *
+ * 通过 useWidgetQuery 查询 apollo-router → core-edu 子图的 myClasses 数据。
+ * 切换班级时写入 URL Search Params（classId），grades-widget 等插件自动响应。
+ *
+ * 关联：portal-shell spec §5.2.1 URL 驱动、M8 验收
+ */
+import { gql } from "@apollo/client";
+import { useRouter, useSearchParams } from "next/navigation";
+import { useWidgetQuery } from "@/lib/useWidgetQuery";
+import { PluginSkeleton } from "@/shell/PluginLoader";
+import type { PluginProps } from "@/lib/types";
+
+const GET_MY_CLASSES = gql`
+  query GetMyClasses {
+    myClasses {
+      id
+      name
+    }
+  }
+`;
+
+interface MyClassesQueryData {
+  myClasses: Array<{ id: string; name: string }>;
+}
+
+export default function ClassSelector(_props: PluginProps): React.ReactElement {
+  const router = useRouter();
+  const searchParams = useSearchParams();
+  const currentClassId = searchParams.get("classId") ?? "";
+
+  const { data, loading } = useWidgetQuery<
+    MyClassesQueryData,
+    Record<string, never>
+  >(GET_MY_CLASSES, {});
+
+  const handleSelect = (classId: string): void => {
+    const params = new URLSearchParams(searchParams.toString());
+    params.set("classId", classId);
+    router.push(`?${params.toString()}`);
+  };
+
+  if (loading && !data) {
+    return <PluginSkeleton variant="list" />;
+  }
+
+  const classes = data?.myClasses ?? [];
+
+  return (
+    <div>
+      <p className="text-small text-ink-muted">班级</p>
+      <select
+        value={currentClassId}
+        onChange={(e) => handleSelect(e.target.value)}
+        className="mt-xs w-full rounded-button border border-rule bg-surface px-sm py-xs text-small text-ink"
+        aria-label="选择班级"
+      >
+        <option value="">请选择班级</option>
+        {classes.map((c) => (
+          <option key={c.id} value={c.id}>
+            {c.name}
+          </option>
+        ))}
+      </select>
+    </div>
+  );
+}

apps/portal-shell/src/widgets/sidebar/class-selector/plugin.manifest.ts

@@ -0,0 +1,21 @@
+/**
+ * class-selector 插件清单（sidebar）
+ *
+ * 班级选择器，插入 side slot。查询 apollo-router → core-edu 子图 myClasses。
+ * 切换 classId 时写入 URL Search Params，其他插件自动响应。
+ */
+import type { PluginManifest } from "@/lib/types";
+
+export const manifestMeta: Omit<PluginManifest, "Component"> = {
+  pluginId: "class-selector",
+  version: "0.1.0",
+  requiredShellVersion: "^1.0.0",
+  metadata: {
+    displayName: "班级选择",
+    description: "切换当前班级（写入 URL classId）",
+    category: "sidebar",
+    requiredRoles: ["teacher"],
+    defaultSlot: "side",
+    defaultSize: { colSpan: 1, rowSpan: 1 },
+  },
+};