chore: 将前端移动到 client/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

client/src/components/submissions/FlagCell.vue

@@ -0,0 +1,74 @@
+<template>
+  <n-popover v-if="isAdmin" trigger="click">
+    <template #trigger>
+      <span :style="dotStyle" />
+    </template>
+    <n-space vertical size="small">
+      <n-button
+        v-for="opt in FLAG_OPTIONS"
+        :key="opt.value"
+        text
+        @click="$emit('update:flag', opt.value)"
+      >
+        <span style="display: flex; align-items: center; gap: 6px">
+          <span
+            :style="{
+              display: 'inline-block',
+              width: '10px',
+              height: '10px',
+              borderRadius: '50%',
+              backgroundColor: opt.color,
+            }"
+          />
+          {{ opt.label }}
+        </span>
+      </n-button>
+      <n-button
+        v-if="flag"
+        text
+        block
+        type="error"
+        @click="$emit('update:flag', null)"
+      >
+        清除
+      </n-button>
+    </n-space>
+  </n-popover>
+  <span v-else :style="dotStyle" />
+</template>
+
+<script setup lang="ts">
+import { computed } from "vue"
+import type { FlagType } from "../../utils/type"
+
+const FLAG_OPTIONS: {
+  value: NonNullable<FlagType>
+  color: string
+  label: string
+}[] = [
+  { value: "red", color: "#e03030", label: "值得展示" },
+  { value: "blue", color: "#2080f0", label: "需要讲解" },
+  { value: "green", color: "#18a058", label: "优秀作品" },
+  { value: "yellow", color: "#f0a020", label: "需要改进" },
+]
+
+const props = defineProps<{
+  flag: FlagType
+  isAdmin: boolean
+}>()
+
+defineEmits<{ "update:flag": [value: FlagType] }>()
+
+const dotStyle = computed(() => {
+  const match = FLAG_OPTIONS.find((f) => f.value === props.flag)
+  return {
+    display: "inline-block",
+    width: "12px",
+    height: "12px",
+    borderRadius: "50%",
+    backgroundColor: match ? match.color : "transparent",
+    border: match ? "none" : "1px dashed #ccc",
+    cursor: props.isAdmin ? "pointer" : "default",
+  }
+})
+</script>