rack：fan 命令放行保持时间 sec，风扇断电显示「停」

Co-Authored-By: Claude Opus 5.5 <[email protected]>

rack/frontend/src/pages/Board.vue

@@ -46,9 +46,10 @@
         <div class="g"><div class="gh"><span class="gk">风扇</span>
             <el-select v-model="fanFloor" size="small" class="floor" aria-label="风扇占空比下限" @change="setFan">
               <el-option :value="0" label="自动" />
-              <el-option v-for="d in [500, 700, 850, 1000]" :key="d" :value="d" :label="`不低于 ${d / 10}%`" />
+              <el-option v-for="d in [300, 500, 700, 850, 1000]" :key="d" :value="d" :label="`不低于 ${d / 10}%`" />
             </el-select></div>
-          <div class="gvs"><span class="gv readout">{{ (b.status.fan?.duty ?? 0) / 10 }}<small>%</small></span>
+          <div class="gvs"><span v-if="b.status.fan?.en === false" class="gv readout" title="板温低于 40 °C：风扇断电（固件 ≥0.1.21）">停</span>
+            <span v-else class="gv readout">{{ (b.status.fan?.duty ?? 0) / 10 }}<small>%</small></span>
             <span v-for="(r, i) in b.status.fan?.rpm || []" :key="i" class="gv sm readout" :class="{ bad: b.status.fan?.stall?.[i] }">{{ r ?? '—' }}<small>rpm</small></span></div></div>
         <div class="g"><div class="gh"><span class="gk">巡检</span></div>
           <div class="gvs"><span class="gv readout">{{ b.status.safety?.cycles }}<small>圈</small></span>