feat(settings,questions,school,textbooks): add brand config, question components, school dialogs, textbooks hooks

settings:

- Add actions-brand, brand-config, data-access-brand for brand management

- Add admin-file-upload-card, admin-notification-config-card, admin-school-info-card, admin-security-policy-card

- Add ai-provider-delete-dialog, ai-provider-selector, brand-config-card

- Add security-recent-logins-section, security-two-factor-section

- Add config/profile-overview-config, data-access-profile-overview, lib/system-settings-utils

questions:

- Add batch-operations, import-export-buttons, knowledge-point-selector, options-editor

- Add question-bank-results-client, question-cascade-filter, question-content-renderer, utils

school:

- Add grade-delete-dialog, grade-form-dialog, grade-list-toolbar, grade-overview-cards

- Add use-grade-data hook

textbooks:

- Add textbook-form-fields component

- Add use-kp-create, use-kp-delete, use-kp-update hooks

src/modules/questions/utils/parse-content.ts

@@ -0,0 +1,128 @@
+/**
+ * 题目内容类型定义与类型守卫。
+ *
+ * 题目 content 存储为 JSON（unknown），实际结构为：
+ * - { text: string } — 简答题/判断题
+ * - { text: string, options: QuestionOption[] } — 选择题
+ * - { text: string, options: QuestionOption[], answer?: string, explanation?: string } — 完整结构
+ *
+ * 所有从 unknown 到具体类型的转换必须使用本文件的类型守卫函数，
+ * 禁止使用 `as` 断言。
+ */
+
+/** 选择题选项 */
+export interface QuestionOption {
+  id: string
+  text: string
+  isCorrect: boolean
+}
+
+/** 题目内容结构化类型 */
+export interface QuestionContent {
+  text: string
+  options?: QuestionOption[]
+  answer?: string
+  explanation?: string
+}
+
+/** 类型守卫：判断值是否为字符串 */
+function isString(value: unknown): value is string {
+  return typeof value === "string"
+}
+
+/** 类型守卫：判断值是否为非 null 对象 */
+function isNonNullObject(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null
+}
+
+/** 类型守卫：判断值是否为 QuestionOption */
+function isQuestionOption(value: unknown): value is QuestionOption {
+  if (!isNonNullObject(value)) return false
+  const id = value.id
+  const text = value.text
+  const isCorrect = value.isCorrect
+  return (
+    (isString(id) || id === undefined) &&
+    isString(text) &&
+    typeof isCorrect === "boolean"
+  )
+}
+
+/** 类型守卫：判断值是否为 QuestionOption 数组 */
+function isQuestionOptionArray(value: unknown): value is QuestionOption[] {
+  return Array.isArray(value) && value.every(isQuestionOption)
+}
+
+/**
+ * 从 unknown 安全解析为 QuestionContent。
+ *
+ * 处理以下情况：
+ * - 字符串：转为 { text: string }
+ * - 对象：提取 text/options/answer/explanation 字段
+ * - null/undefined：返回 { text: "" }
+ * - 其他：JSON.stringify 后转为 { text }
+ *
+ * @example
+ * const content = parseQuestionContent(question.content)
+ * console.log(content.text)        // 题干文本
+ * console.log(content.options)      // 选项列表（选择题）
+ */
+export function parseQuestionContent(raw: unknown): QuestionContent {
+  if (isString(raw)) {
+    return { text: raw }
+  }
+
+  if (isNonNullObject(raw)) {
+    const text = isString(raw.text) ? raw.text : ""
+    const optionsRaw = raw.options
+    const options = isQuestionOptionArray(optionsRaw)
+      ? optionsRaw.map((opt) => ({
+          id: opt.id ?? opt.text,
+          text: opt.text,
+          isCorrect: opt.isCorrect,
+        }))
+      : undefined
+    const answer = isString(raw.answer) ? raw.answer : undefined
+    const explanation = isString(raw.explanation) ? raw.explanation : undefined
+
+    return { text, options, answer, explanation }
+  }
+
+  if (raw == null) {
+    return { text: "" }
+  }
+
+  try {
+    return { text: JSON.stringify(raw) }
+  } catch {
+    return { text: "" }
+  }
+}
+
+/**
+ * 从 QuestionContent 提取纯文本预览（截断到指定长度）。
+ *
+ * @param raw - 原始 content（unknown）
+ * @param maxLength - 最大长度，默认 80
+ */
+export function getQuestionPreview(raw: unknown, maxLength = 80): string {
+  const content = parseQuestionContent(raw)
+  return content.text.slice(0, maxLength)
+}
+
+/**
+ * 从 QuestionContent 提取选项列表（用于表单回填）。
+ *
+ * @returns 选项数组，无选项时返回 undefined
+ */
+export function getQuestionOptions(raw: unknown): QuestionOption[] | undefined {
+  const content = parseQuestionContent(raw)
+  return content.options
+}
+
+/**
+ * 从 QuestionContent 提取纯文本（用于 AI 变体生成等场景）。
+ */
+export function getQuestionText(raw: unknown): string {
+  return parseQuestionContent(raw).text
+}