feat(dashboard,diagnostic,elective): add widgets, layout, parent dashboard, role-config, services, elective components

dashboard:

- Add comparison-badge, dashboard-notification-widget, dashboard-responsive-layout, dashboard-time-range-filter

- Add parent-dashboard components directory

- Add config, hooks, and services directories

diagnostic:

- Add role-config and services directory

elective:

- Add elective-course-detail, elective-stats-cards, parent-selection-view components

- Add data-access-settings and data-access-stats

src/modules/diagnostic/services/diagnostic-service-context.tsx

@@ -0,0 +1,46 @@
+"use client"
+
+import { createContext, useContext, type ReactNode } from "react"
+
+import type { DiagnosticService } from "./diagnostic-service"
+
+/**
+ * v2-P1-4: 诊断模块服务 Context。
+ *
+ * 组件通过 useDiagnosticService() 获取服务实现，
+ * 而非直接 import actions，实现依赖反转。
+ *
+ * 默认由 DefaultDiagnosticServiceProvider 注入真实实现（调用 Server Actions）；
+ * 测试时可注入 mock 实现以隔离组件测试。
+ */
+const DiagnosticServiceContext = createContext<DiagnosticService | null>(null)
+
+interface DiagnosticServiceProviderProps {
+  service: DiagnosticService
+  children: ReactNode
+}
+
+export function DiagnosticServiceProvider({
+  service,
+  children,
+}: DiagnosticServiceProviderProps): ReactNode {
+  return (
+    <DiagnosticServiceContext.Provider value={service}>
+      {children}
+    </DiagnosticServiceContext.Provider>
+  )
+}
+
+/**
+ * 获取诊断模块服务。
+ * 必须在 DiagnosticServiceProvider 内部使用。
+ */
+export function useDiagnosticService(): DiagnosticService {
+  const service = useContext(DiagnosticServiceContext)
+  if (!service) {
+    throw new Error(
+      "useDiagnosticService must be used within a DiagnosticServiceProvider",
+    )
+  }
+  return service
+}