fix(界面): 能点的文字平时就是绿色，不用再把鼠标移上去才看得出能点

首页「全部」、提交详情的用户名和题名、题目页「点开看全部」「有 N 道差一点」、
班级对抗的班级名、知识点、后台标题等 30 多处原来和正文同色，鼠标移上去才变色，
手机上根本没有「移上去」。现在一律主题绿，移上去加下划线；没设颜色的文字按钮补上
type="primary"。排名名字列、整行可点的列表、后台 quaternary 次要按钮不动。

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

apps/web/src/oj/classroom/board.vue

@@ -467,7 +467,7 @@ function lastText(student: ClassBoardStudent) {
         <span v-if="board.assignedAt" class="assigned">
           {{ parseTime(board.assignedAt, "HH:mm") }} {{ board.assignedBy }} 布置
         </span>
-        <n-button text class="edit" @click="editing = true">
+        <n-button text type="primary" class="edit" @click="editing = true">
           <template #icon><Icon icon="ph:pencil-simple" /></template>
           {{ board.source === "teacher" ? "改" : "布置" }}
         </n-button>
@@ -998,12 +998,12 @@ function lastText(student: ClassBoardStudent) {
 .panel-title {
   font-size: 16px;
   font-weight: 600;
-  color: inherit;
+  color: v-bind("theme.primaryColor");
   text-decoration: none;
 }
 
 .panel-title:hover {
-  color: v-bind("theme.primaryColor");
+  text-decoration: underline;
 }
 
 .groups {