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/exams/components/exam-ai-generator.tsx

@@ -2,6 +2,7 @@
 
 import type { Control, UseFormReturn } from "react-hook-form"
 import { useTranslations } from "next-intl"
+import Link from "next/link"
 import { Settings } from "lucide-react"
 import {
   FormField,
@@ -27,15 +28,6 @@ import {
   CardHeader,
   CardTitle,
 } from "@/shared/components/ui/card"
-import {
-  Dialog,
-  DialogContent,
-  DialogDescription,
-  DialogHeader,
-  DialogTitle,
-  DialogTrigger,
-} from "@/shared/components/ui/dialog"
-import { AiProviderSettingsCard } from "@/modules/settings/components/ai-provider-settings-card"
 import type { AiProviderSummary } from "@/modules/settings/actions"
 import { formatDateTime } from "@/shared/lib/utils"
 import type { ExamFormValues, PreviewBackgroundTask } from "./exam-form-types"
@@ -47,10 +39,6 @@ type ExamAiGeneratorProps = {
   aiProviders: AiProviderSummary[]
   setAiProviders: (providers: AiProviderSummary[]) => void
   loadingAiProviders: boolean
-  providerDialogOpen: boolean
-  setProviderDialogOpen: (open: boolean) => void
-  providerDialogKey: number
-  setProviderDialogKey: (key: number | ((prev: number) => number)) => void
   handlePreview: () => void
   handleBackgroundPreview: () => void
   previewLoading: boolean
@@ -62,15 +50,11 @@ type ExamAiGeneratorProps = {
 }
 
 export function ExamAiGenerator({
-  form,
+  form: _form,
   control,
   aiProviders,
-  setAiProviders,
+  setAiProviders: _setAiProviders,
   loadingAiProviders,
-  providerDialogOpen,
-  setProviderDialogOpen,
-  providerDialogKey,
-  setProviderDialogKey,
   handlePreview,
   handleBackgroundPreview,
   previewLoading,
@@ -104,41 +88,12 @@ export function ExamAiGenerator({
             <FormItem>
               <div className="flex items-center justify-between gap-2">
                 <FormLabel>{t("provider.label")}</FormLabel>
-                <Dialog
-                  open={providerDialogOpen}
-                  onOpenChange={(open) => {
-                    setProviderDialogOpen(open)
-                    if (open) {
-                      setProviderDialogKey((value) => value + 1)
-                    }
-                  }}
-                >
-                  <DialogTrigger asChild>
-                    <Button type="button" variant="ghost" size="sm" className="h-7 px-2 text-muted-foreground hover:text-foreground">
-                      <Settings className="mr-1 h-3.5 w-3.5" />
-                      {t("provider.manage")}
-                    </Button>
-                  </DialogTrigger>
-                  <DialogContent className="sm:max-w-[960px]">
-                    <DialogHeader>
-                      <DialogTitle>{t("provider.manageTitle")}</DialogTitle>
-                      <DialogDescription>
-                        {t("provider.manageDescription")}
-                      </DialogDescription>
-                    </DialogHeader>
-                    <AiProviderSettingsCard
-                      key={providerDialogKey}
-                      initialMode="new"
-                      onProvidersChanged={(rows) => {
-                        setAiProviders(rows)
-                        const preferred = rows.find((item) => item.isDefault) ?? rows[0]
-                        if (preferred) {
-                          form.setValue("aiProviderId", preferred.id)
-                        }
-                      }}
-                    />
-                  </DialogContent>
-                </Dialog>
+                <Button asChild type="button" variant="ghost" size="sm" className="h-7 px-2 text-muted-foreground hover:text-foreground">
+                  <Link href="/admin/ai-settings">
+                    <Settings className="mr-1 h-3.5 w-3.5" />
+                    {t("provider.manage")}
+                  </Link>
+                </Button>
               </div>
               <Select value={field.value} onValueChange={field.onChange} disabled={loadingAiProviders}>
                 <FormControl>

src/modules/exams/components/exam-form.tsx

@@ -25,8 +25,6 @@ export type { ExamFormValues } from "./exam-form-types"
 export function ExamForm() {
   const router = useRouter()
   const [isPending, startTransition] = useTransition()
-  const [providerDialogOpen, setProviderDialogOpen] = useState(false)
-  const [providerDialogKey, setProviderDialogKey] = useState(0)
   const [subjects, setSubjects] = useState<{ id: string; name: string }[]>([])
   const [loadingSubjects, setLoadingSubjects] = useState(true)
   const [grades, setGrades] = useState<{ id: string; name: string }[]>([])
@@ -219,10 +217,6 @@ export function ExamForm() {
               aiProviders={aiProviders}
               setAiProviders={setAiProviders}
               loadingAiProviders={loadingAiProviders}
-              providerDialogOpen={providerDialogOpen}
-              setProviderDialogOpen={setProviderDialogOpen}
-              providerDialogKey={providerDialogKey}
-              setProviderDialogKey={setProviderDialogKey}
               handlePreview={preview.handlePreview}
               handleBackgroundPreview={preview.handleBackgroundPreview}
               previewLoading={preview.previewLoading}