feat(ai): V2 深度增强 — SSE 流式/全局助手/内容安全/多角色覆盖

对标 Khanmigo/Duolingo Max/Squirrel AI/Century Tech 实现：

- SSE 流式响应：createAiChatCompletionStream AsyncGenerator + /api/ai/chat/stream SSE 端点 + useAiChatStream hook（AbortController 停止生成 + localStorage 持久化）

- Markdown 渲染：AiMarkdownRenderer（react-markdown + remark-gfm + 代码块/表格/列表 + hover 复制按钮）

- 全局 AI 助手：AiAssistantWidget 浮动按钮 + Sheet 侧抽屉 + usePathname 路由推断上下文（7 类场景系统提示）+ dashboard layout 全局注入 AiClientProvider

- 内容安全：content-safety.ts 多层过滤（输入/输出安全过滤 + 每日限制 student 50/teacher 200/parent 30/admin 500 + 学生苏格拉底模式），COPPA/FERPA K12 合规

- 多角色 AI 覆盖：家长端 AiChildSummary（学情摘要）+ 管理员端 AiUsageDashboard（使用监控）+ 学生端 AiStudyPath（个性化学习路径）

- i18n 修复：8 处错误键引用 + zh-CN/en ai.json 全面扩展

- 架构文档 004/005 同步更新

src/modules/ai/schema.ts

@@ -132,3 +132,74 @@ export const WeaknessAnalysisResultSchema = z.object({
   studyPlan: z.string().min(1),
   recommendedResources: z.array(z.string()),
 })
+
+// ---------------------------------------------------------------------------
+// 家长学情摘要校验
+// ---------------------------------------------------------------------------
+
+export const ChildSummaryInputSchema = z.object({
+  studentId: z.string().min(1),
+  studentName: z.string().optional(),
+  grade: z.string().optional(),
+  recentGrades: z
+    .array(
+      z.object({
+        subject: z.string().min(1),
+        score: z.number(),
+        maxScore: z.number(),
+        trend: z.enum(["up", "down", "stable"]),
+      })
+    )
+    .optional(),
+  attendanceRate: z.number().min(0).max(1).optional(),
+  errorBookSummary: z
+    .object({
+      totalErrors: z.number().int().min(0),
+      topWeakSubjects: z.array(z.string()),
+      masteryTrend: z.enum(["improving", "declining", "stable"]),
+    })
+    .optional(),
+  homeworkCompletionRate: z.number().min(0).max(1).optional(),
+})
+
+export const ChildSummaryResultSchema = z.object({
+  overallAssessment: z.string().min(1),
+  strengths: z.array(z.string()),
+  areasForImprovement: z.array(z.string()),
+  familyTutoringSuggestions: z.array(z.string()),
+  nextSteps: z.array(z.string()),
+})
+
+// ---------------------------------------------------------------------------
+// 学习路径推荐校验
+// ---------------------------------------------------------------------------
+
+export const StudyPathInputSchema = z.object({
+  studentId: z.string().min(1),
+  subject: z.string().optional(),
+  currentMastery: z
+    .array(
+      z.object({
+        knowledgePoint: z.string().min(1),
+        masteryLevel: z.number().min(0).max(5),
+        errorCount: z.number().int().min(0),
+      })
+    )
+    .optional(),
+  learningGoal: z.string().optional(),
+})
+
+export const StudyPathResultSchema = z.object({
+  currentLevel: z.string().min(1),
+  learningPath: z.array(
+    z.object({
+      step: z.number().int().min(1),
+      knowledgePoint: z.string().min(1),
+      status: z.enum(["mastered", "in_progress", "needs_work"]),
+      recommendedAction: z.string().min(1),
+      estimatedTime: z.string().min(1),
+    })
+  ),
+  summary: z.string().min(1),
+  motivation: z.string().min(1),
+})