fix(bom): 另存为版本自增基准改响应式，修复 V1.1→V1.2 未升级

- originalVersion/currentBomNo 为普通 let，computed 读不到变化；且 handleSaveAs 在赋值前就算版本候选，导致从 V1.1 另存得到 V1.1 覆盖原版本
- 新增响应式 upgradeBaseVersion/upgradeBaseBomNo，versionOptions 改读 ref；handleSaveAs 先锁定基准再计算
- 修复后：V1.1→V1.2、V1.9→V1.10、主版本→V2.0，占用号自动跳过

inventory-web/src/views/bom/BomManage.vue

@@ -424,6 +424,9 @@ const isSaveAsMode = ref(false)
 const isReadOnlyMode = ref(false)
 let originalVersion = ''
 let currentBomNo = ''
+// ★ 版本升级的响应式基准（plain let 不是响应式，computed 读不到变化 → 1.1 升次版本会算出错的候选）
+const upgradeBaseVersion = ref('')
+const upgradeBaseBomNo = ref('')
 let originalChildren: ChildRow[] = []
 let pendingDraftBomNo = ''
 let pendingDraftVersion = ''
@@ -617,11 +620,11 @@ const form = reactive({
 const pureBomNo = computed(() => form.bom_no)
 
 const versionOptions = computed(() => {
-  const ver = originalVersion || 'V1.0'
+  const ver = upgradeBaseVersion.value || 'V1.0'
   const allItems: any[] = []
   groupCache.value.forEach((items) => allItems.push(...items))
   const occupiedVersions = new Set(
-    allItems.filter((item: any) => item.bom_no === currentBomNo).map((item: any) => item.version)
+    allItems.filter((item: any) => item.bom_no === upgradeBaseBomNo.value).map((item: any) => item.version)
   )
   const getNextMinor = (baseMajor: number, baseMinor: number): string => {
     let minor = baseMinor + 1
@@ -1008,10 +1011,15 @@ const handleSaveAs = async (row: any) => {
     form.bom_no = (raw.parent_spec || row.bom_no).split('/')[0].trim()
     form.remark = raw.remark || ''
     form.versionUpgradeType = 'minor'
-    form.version = versionOptions.value?.minor || 'V1.1'
 
+    // ★ 先锁定升级基准（原版本号 + 该 BOM），再计算目标版本，保证 V1.1 → V1.2 等正确且跳过已占用号
     originalVersion = raw.version || ''
     currentBomNo = row.bom_no
+    upgradeBaseVersion.value = originalVersion
+    upgradeBaseBomNo.value = currentBomNo
+    const upgradeOpts = versionOptions.value
+    form.version = upgradeOpts?.minor || upgradeOpts?.major || 'V1.1'
+
     originalChildren = JSON.parse(JSON.stringify(form.children))
     originalDraftHash.value = getDraftHash()
 
@@ -1207,6 +1215,8 @@ const resetForm = () => {
   isReadOnlyMode.value = false
   originalVersion = ''
   currentBomNo = ''
+  upgradeBaseVersion.value = ''
+  upgradeBaseBomNo.value = ''
   childSearchKeyword.value = ''
   parentNameInput.value = ''
   originalDraftHash.value = ''