feat(ai): 新增 AI 模块并集成至备课/错题集/试卷/改题四大业务场景

- 新增 src/modules/ai 独立模块，遵循三层架构（actions → services → shared/lib/ai）
- 通过 AiClientProvider + useAiClient 实现 React Context 依赖注入，业务组件零直接 import
- 6 个 Server Actions 均调用 requirePermission() 权限校验，返回 ActionState<T>
- withAiTracking 统一埋点，覆盖 chat/similar_question/grading_assist/lesson_content/question_variant/weakness_analysis
- 集成场景：作业批改 AiGradingAssist、错题集 AiErrorBookAnalysis、备课 AiLessonContentGenerator、试卷 AiQuestionVariantGenerator
- 全量 i18n（en/zh-CN ai.json），Error Boundary + Skeleton 边界处理
- 同步架构图 004/005，新增审计报告 ai-module-audit-report.md

src/modules/lesson-preparation/ai-suggest.ts

@@ -1,24 +1,43 @@
 import "server-only";
 
+import { z } from "zod";
 import { env } from "@/env.mjs";
 import { createAiChatCompletion } from "@/shared/lib/ai";
 import {
   getKnowledgePointsByTextbookId,
   getKnowledgePointsByChapterId,
 } from "@/modules/textbooks/data-access";
-import type { LessonPlanDocument } from "./types";
+
+const SuggestedKpSchema = z.object({
+  id: z.string().min(1),
+  name: z.string().min(1),
+  reason: z.string(),
+});
+
+const SuggestedKpListSchema = z.array(SuggestedKpSchema);
+
+/** 从 unknown 节点安全提取文本（类型守卫从 unknown 收窄） */
+const extractNodeText = (node: unknown): string => {
+  if (!node || typeof node !== "object") return ""
+  // 从 unknown 收窄为 Record<string, unknown> 以进行字段检查
+  const record = node as Record<string, unknown>
+  const data = record.data
+  if (!data || typeof data !== "object") return ""
+  // 从 unknown 收窄为 Record<string, unknown> 以进行字段检查
+  const dataRecord = data as Record<string, unknown>
+  const html = typeof dataRecord.html === "string" ? dataRecord.html : ""
+  const sourceText = typeof dataRecord.sourceText === "string" ? dataRecord.sourceText : ""
+  return html || sourceText || ""
+}
 
 export async function suggestKnowledgePoints(
-  doc: LessonPlanDocument,
+  doc: { nodes: unknown[] },
   textbookId?: string,
   chapterId?: string,
 ): Promise<{ id: string; name: string; reason: string }[]> {
   // 1. 提取课案纯文本
   const text = doc.nodes
-    .map((b) => {
-      const d = b.data as { html?: string; sourceText?: string };
-      return d.html ?? d.sourceText ?? "";
-    })
+    .map((b) => extractNodeText(b))
     .join("\n")
     .slice(0, 3000);
 
@@ -51,14 +70,12 @@ ${text}
     // 尝试从返回内容中提取 JSON 数组
     const jsonMatch = content.match(/\[[\s\S]*\]/);
     if (!jsonMatch) return [];
-    const parsed = JSON.parse(jsonMatch[0]) as {
-      id: string;
-      name: string;
-      reason: string;
-    }[];
+    const parsed: unknown = JSON.parse(jsonMatch[0]);
+    const validated = SuggestedKpListSchema.safeParse(parsed);
+    if (!validated.success) return [];
     // 过滤掉不在候选池中的 id
     const validIds = new Set(kpList.map((k) => k.id));
-    return parsed.filter((p) => validIds.has(p.id));
+    return validated.data.filter((p) => validIds.has(p.id));
   } catch {
     return [];
   }