fix: DRATIO 统一逻辑方向，改为 '分享率<X' 与其他规则保持一致

所有规则现在统一: 指标越过阈值 → 风险
- H&R≥5 → 封号
- 下载量≥100GB且分享率<0.3 → 封号
- 距上次登录>150天 → 封号

web/src/views/RiskRules.vue

@@ -131,7 +131,7 @@
                 <div v-for="(lv, li) in (rule.levels||[])" :key="li" class="field-row">
                   <span class="field-label">下载量 ≥</span>
                   <el-input v-model.number="lv.threshold" size="small" type="number" placeholder="GB" @input="sync" style="width:90px" />
-                  <span class="field-hint">GB 时，要求分享率 ≥</span>
+                  <span class="field-hint">GB 时，分享率 &lt;</span>
                   <el-input v-model.number="lv.ratio" size="small" type="number" :step="0.1" placeholder="分享率" @input="sync" style="width:80px" />
                   <el-button size="small" type="danger" text :icon="Delete" @click="removeDRatioLevel(rule, li)" />
                 </div>
@@ -273,7 +273,7 @@ const presets = [
   // 新人考核
   { name:'新人考核',           type:'TASK', threshold:30, unit:'天', description:'新注册用户需在考核周期内完成各项要求' },
   // 动态分享率
-  { name:'动态分享率',         type:'DRATIO', levels:[{threshold:100,ratio:0.3},{threshold:500,ratio:0.5},{threshold:1000,ratio:0.8}], description:'下载量分级控制分享率' },
+  { name:'动态分享率',         type:'DRATIO', levels:[{threshold:100,ratio:0.3},{threshold:500,ratio:0.5},{threshold:1000,ratio:0.8}], description:'下载量越大，允许的最低分享率越低' },
   // 等级豁免
   { name:'等级豁免',           type:'EXEMPT', permRank:'Elite User', sealExemptRank:'Power User', description:'达到等级的账号可豁免清理' },
 ]
@@ -338,7 +338,7 @@ const ruleText = (r) => {
   const cond = condLabel(r.condition)
   const val = `${metric}${cond}${r.threshold}${r.unit||''}`
   if (r.type === 'DRATIO') {
-    const levels = (r.levels||[]).map(l => `下载量≥${l.threshold}GB时要求分享率≥${l.ratio}`).join('，')
+    const levels = (r.levels||[]).map(l => `下载量≥${l.threshold}GB时分享率<${l.ratio}`).join('，')
     return `动态分享率：${levels} → <span style="color:#e6a23c;font-weight:500">封号（缓刑7天）</span>${appText}`
   }
   if (r.type === 'RATIO') {