feat(returnmatch): mark yeeke returns unavailable when a complete sync drops them (#338)

A COMPLETE yeeke sync run (natural page-walk end, not stopped by a
duplicate-fingerprint break or MaxPages exhaustion) that also wrote zero
record failures now flips any yeeke_return_package/yeeke_return_item still
"ok" from before the run to sync_status="missing" with missing_since
stamped, in one transaction. Rows are never deleted. A 20% safety valve
skips marking (and records why in error_message) when the candidate count
would be too large; a reappearing record recovers to "ok" with
missing_since cleared.

returnmatch.availableReturnPool now excludes missing items/packages from
matching, without auto-cancelling any existing active match; List()/Detail()
surface syncStatus/missingSince so the SYB products match column, its
compare dialog, and the yeeke returns list can warn or label rows as
unavailable.

Adds migration 1789800900000_return_missing (AutoMigrate alone does not
reach existing databases).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NTDbDcwbDw1TSAcE6wfh2F

web/src/views/goauto/syb-products/index.vue

@@ -62,6 +62,7 @@
                     <div class="muted">销毁截止：{{ formatMatchDeadline(returnMatchByProductId[row.id].destroyDeadline) }}</div>
                   </div>
                 </div>
+                <el-alert v-if="returnMatchByProductId[row.id].syncStatus === 'missing'" title="退货已不在 yeeke 列表" type="error" :closable="false" show-icon class="return-missing-alert" />
                 <div class="quick-link-actions">
                   <el-button type="primary" link @click="openMatchDetail(returnMatchByProductId[row.id].id)">查看对比</el-button>
                   <el-button v-if="canPurchase" type="primary" link @click="openMatchDetail(returnMatchByProductId[row.id].id, true)">备注</el-button>
@@ -221,6 +222,7 @@
               </div>
               <div class="split-col">
                 <h3 class="section-title">yeeke 退货商品</h3>
+                <el-alert v-if="matchDetail.data.yeeke && matchDetail.data.yeeke.syncStatus === 'missing'" title="退货已不在 yeeke 列表" type="error" :closable="false" show-icon class="notice" />
                 <el-descriptions :column="1" border size="small" v-if="matchDetail.data.yeeke">
                   <el-descriptions-item label="退货订单号">{{ matchDetail.data.yeeke.orderSn }}</el-descriptions-item>
                   <el-descriptions-item label="商品ID">{{ matchDetail.data.yeeke.itemId }}</el-descriptions-item>
@@ -838,6 +840,7 @@ export default {
 .link{color:#1677ff;cursor:pointer}
 .shopee-title{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
 .notice{margin-bottom:16px}
+.return-missing-alert{margin:6px 0}
 .compact-notice{margin-bottom:12px}
 .purchase-summary{display:flex;flex-wrap:wrap;gap:12px 24px;margin-bottom:16px;padding:12px 16px;border:1px solid #dbeafe;border-radius:8px;background:#f8fafc}.purchase-summary strong{font-variant-numeric:tabular-nums;color:#1e40af}.success-text{color:#166534}.warning-text{color:#b45309}.danger-text,.purchase-reason{color:#b91c1c}.purchase-reason{margin-top:4px;font-size:12px;line-height:1.45}.purchase-settings{margin-bottom:12px}.field-help{margin-left:12px;color:#909399;font-size:12px}.ellipsis{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.image-search-tag{margin-left:6px;vertical-align:middle}
 .spec-match-summary{gap:8px 24px}

web/src/views/goauto/yeeke-returns/index.vue

@@ -66,6 +66,12 @@
               <el-tag v-else :type="claimStatusMeta(row.claimStatus).type">{{ claimStatusMeta(row.claimStatus).label }}</el-tag>
             </template>
           </el-table-column>
+          <el-table-column label="yeeke 可用性" min-width="150">
+            <template #default="{ row }">
+              <el-tag v-if="row.syncStatus === 'missing'" type="danger" effect="plain">不可用（yeeke 列表中已不存在）</el-tag>
+              <span v-else class="muted">—</span>
+            </template>
+          </el-table-column>
           <el-table-column label="上架时间" min-width="150"><template #default="{ row }">{{ formatTime(row.claimTime) }}</template></el-table-column>
           <el-table-column label="销毁截止" min-width="150"><template #default="{ row }">{{ formatTime(row.destroyDeadLine) }}</template></el-table-column>
           <el-table-column label="最近同步" min-width="150"><template #default="{ row }">{{ formatTime(row.lastSyncedAt) }}</template></el-table-column>