refactor(grades,diagnostic): 成绩和学情诊断模块审计修复

P0-1: 10 个页面补充 requirePermission 权限校验
P0-2: diagnostic/data-access-reports.ts 移除直查 users 表，改用 getUserNamesByIds
P0-3: 新增 grade/grades/diagnostic 三组 i18n 翻译文件（zh-CN/en）
P0-4: 新增 /management/grade 重定向页面

P1-2: 抽取 toNumber/normalize/buildScopeClassFilter 到 lib/grade-utils.ts
P1-3: 为 12 个 Action 新增 Zod safeParse 校验（schema.ts +12 查询 schema）
P1-4: 修复 as 断言违规，改用类型守卫函数

P2-2: 移除 diagnostic 组件中 Tailwind 任意值

同步更新架构图文档 004 和 005

src/modules/grades/components/grade-distribution-chart.tsx

@@ -18,6 +18,30 @@ interface GradeDistributionChartProps {
   data: GradeDistributionResult | null
 }
 
+interface DistributionTooltipItem {
+  label: string
+  count: number
+  percentage: number
+}
+
+interface DistributionTooltipPayload {
+  payload?: DistributionTooltipItem
+}
+
+function isDistributionTooltipPayload(v: unknown): v is DistributionTooltipPayload {
+  if (typeof v !== "object" || v === null) return false
+  const obj = v as Record<string, unknown>
+  const inner = obj.payload
+  if (inner === undefined || inner === null) return true
+  if (typeof inner !== "object") return false
+  const item = inner as Record<string, unknown>
+  return (
+    typeof item.label === "string" &&
+    typeof item.count === "number" &&
+    typeof item.percentage === "number"
+  )
+}
+
 export function GradeDistributionChart({ data }: GradeDistributionChartProps) {
   const isEmpty = !data || data.totalCount === 0
 
@@ -64,7 +88,8 @@ export function GradeDistributionChart({ data }: GradeDistributionChartProps) {
         tooltipClassName="w-[200px]"
         cellColors={BUCKET_COLORS}
         tooltipFormatter={(payload: unknown) => {
-          const item = (payload as { payload?: { label: string; count: number; percentage: number } })?.payload
+          if (!isDistributionTooltipPayload(payload)) return null
+          const item = payload.payload
           if (!item) return null
           return (
             <div className="flex w-full flex-col gap-0.5">