feat(排名): 个性签名直接写在名单上，不用再指着小引号才看得到

- 桌面：写了签名的同学名字下面多一行，把签名写出来（一行二十来个字，长的指上去看全文）；两栏按高度对半分
- 手机：签名从名字后面（只剩三五个字）挪到名字下面一行
- 自己还没写的，名单里自己那行有「写一句个性签名」，和「你」卡点开的是同一个框

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

apps/web/src/oj/rank/components/MoodPopover.vue

@@ -0,0 +1,92 @@
+<script setup lang="ts">
+import { MOOD_MAX } from "@oj2/contract"
+import { updateProfile } from "oj/api"
+import { useUserStore } from "shared/store/user"
+
+/**
+ * 就地改个性签名：「你」卡上的签名、赛道里自己那行的「写一句个性签名」点开的是同一个框。
+ * 触发按钮由调用方放进默认插槽。
+ */
+const props = defineProps<{ mood: string | null }>()
+const emit = defineEmits<{ saved: [mood: string | null] }>()
+
+const message = useMessage()
+const userStore = useUserStore()
+const inputId = useId()
+
+const editing = ref(false)
+const draft = ref("")
+const saving = ref(false)
+
+watch(editing, (open) => {
+  if (open) draft.value = props.mood ?? ""
+})
+
+async function save() {
+  const mood = draft.value.trim()
+  if (mood.length > MOOD_MAX) {
+    message.warning(`个性签名最多 ${MOOD_MAX} 个字`)
+    return
+  }
+  saving.value = true
+  try {
+    await updateProfile({ mood })
+    if (userStore.profile) userStore.profile.mood = mood || null
+    emit("saved", mood || null)
+    editing.value = false
+    message.success(mood ? "签名改好了" : "签名清空了")
+  } catch {
+    message.error("没保存上，再试一次")
+  } finally {
+    saving.value = false
+  }
+}
+</script>
+
+<template>
+  <n-popover
+    v-model:show="editing"
+    trigger="click"
+    placement="bottom-start"
+    :style="{ width: '300px' }"
+  >
+    <template #trigger>
+      <slot />
+    </template>
+    <form class="mood-form" @submit.prevent="save">
+      <label class="mood-label" :for="inputId">个性签名</label>
+      <n-input
+        v-model:value="draft"
+        :input-props="{ id: inputId }"
+        :maxlength="MOOD_MAX"
+        show-count
+        clearable
+        placeholder="写点什么，让大家认识你"
+        autofocus
+      />
+      <div class="mood-actions">
+        <n-button size="small" @click="editing = false">取消</n-button>
+        <n-button size="small" type="primary" attr-type="submit" :loading="saving"> 保存 </n-button>
+      </div>
+    </form>
+  </n-popover>
+</template>
+
+<style scoped>
+.mood-form {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+
+.mood-label {
+  font-size: var(--oj-fs-sec);
+  font-weight: 600;
+}
+
+.mood-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 8px;
+}
+</style>