feat(ai): 统一 AI 配置入口到 /admin/ai-settings

## 新增
- 创建 /admin/ai-settings 统一配置页（AiProviderSettingsCard + AiUsageDashboard）
- admin 侧边栏新增"AI 配置"菜单项（权限 AI_CONFIGURE，图标 Sparkles）
- 新增 deleteAiProvider 数据访问层（事务删除 + 自动转移默认）
- 新增 deleteAiProviderAction Server Action（Zod 校验 + 权限校验）
- AiProviderSettingsCard 新增删除按钮（AlertDialog 确认 + destructive 变体）
- 新增 i18n 翻译键（delete/deleteConfirm/deleteSuccess 等，zh-CN + en）

## 移除
- 从 /settings 移除 AI 标签页（原 VALID_TABS 含 "ai"，现仅 4 标签页）
- 从考试页面移除 AI 配置弹窗（Dialog + AiProviderSettingsCard 内嵌）
- 从 ai-provider-selector.tsx 移除配置弹窗（managePanel/manageOpen props）
- 移除 settings-view.tsx 中 canConfigureAi 逻辑和未使用 import

## 变更
- 考试页面"管理"按钮改为 Link 跳转到 /admin/ai-settings
- ai-provider-selector.tsx"管理"按钮改为 Link 跳转到 /admin/ai-settings
- exam-form.tsx 移除 providerDialogOpen/providerDialogKey 状态
- 修正架构文档 004 中 Action 命名（getAiProvidersAction → getAiProviderSummaries 等）

## 架构文档同步
- 004 更新 settings 模块章节（V3 标记/修正 Action 名称/新增 deleteAiProvider）
- 005 新增 deleteAiProviderAction 节点 + /admin/ai-settings 路由

src/modules/layout/config/navigation.ts

@@ -22,6 +22,7 @@ import {
   BookCopy,
   Files,
   BookX,
+  Sparkles,
 } from "lucide-react"
 import type { LucideIcon } from "lucide-react"
 import { Permissions } from "@/shared/types/permissions"
@@ -134,6 +135,12 @@ export const NAV_CONFIG: Partial<Record<Role, NavItem[]>> = {
       href: "/admin/error-book",
       permission: Permissions.ERROR_BOOK_ANALYTICS_READ,
     },
+    {
+      title: "课案管理",
+      icon: PenTool,
+      href: "/admin/lesson-plans",
+      permission: Permissions.LESSON_PLAN_READ,
+    },
     {
       title: "Audit Logs",
       icon: ScrollText,
@@ -146,6 +153,12 @@ export const NAV_CONFIG: Partial<Record<Role, NavItem[]>> = {
       ]
     },
     ...COMMON_NAV_ITEMS,
+    {
+      title: "AI 配置",
+      icon: Sparkles,
+      href: "/admin/ai-settings",
+      permission: Permissions.AI_CONFIGURE,
+    },
     {
       title: "Settings",
       icon: Settings,
@@ -268,6 +281,7 @@ export const NAV_CONFIG: Partial<Record<Role, NavItem[]>> = {
       permission: Permissions.GRADE_MANAGE,
       items: [
         { title: "年级班级", href: "/management/grade/classes" },
+        { title: "年级仪表盘", href: "/management/grade/dashboard" },
         { title: "年级洞察", href: "/management/grade/insights" },
       ]
     },
@@ -287,6 +301,7 @@ export const NAV_CONFIG: Partial<Record<Role, NavItem[]>> = {
       permission: Permissions.GRADE_MANAGE,
       items: [
         { title: "年级班级", href: "/management/grade/classes" },
+        { title: "年级仪表盘", href: "/management/grade/dashboard" },
         { title: "年级洞察", href: "/management/grade/insights" },
       ]
     },
@@ -332,6 +347,7 @@ export const NAV_CONFIG: Partial<Record<Role, NavItem[]>> = {
       permission: Permissions.GRADE_MANAGE,
       items: [
         { title: "年级班级", href: "/management/grade/classes" },
+        { title: "年级仪表盘", href: "/management/grade/dashboard" },
         { title: "年级洞察", href: "/management/grade/insights" },
       ]
     },
@@ -392,6 +408,12 @@ export const NAV_CONFIG: Partial<Record<Role, NavItem[]>> = {
       href: "/student/grades",
       permission: Permissions.GRADE_RECORD_READ,
     },
+    {
+      title: "我的课案",
+      icon: PenTool,
+      href: "/student/lesson-plans",
+      permission: Permissions.LESSON_PLAN_READ,
+    },
     {
       title: "Attendance",
       icon: CalendarCheck,
@@ -430,6 +452,12 @@ export const NAV_CONFIG: Partial<Record<Role, NavItem[]>> = {
       href: "/parent/grades",
       permission: Permissions.GRADE_RECORD_READ,
     },
+    {
+      title: "孩子课案",
+      icon: PenTool,
+      href: "/parent/lesson-plans",
+      permission: Permissions.LESSON_PLAN_READ,
+    },
     {
       title: "Attendance",
       icon: CalendarCheck,