fix: 修复批量 Deep Scan 队列显示问题

问题：
- 使用静态的 position 计算 queuePosition，导致队列显示不准确
- 任务实际执行时间不确定，导致队列状态显示错误

修复：
- 使用 processing 变量跟踪正在处理的任务数量
- 动态计算队列数量：queueCount = filesToProcess.length - successCount - failCount - processing
- 确保队列状态实时更新

改进：
- 添加 processing 变量跟踪正在处理的任务
- 在 finally 块中递减 processing 计数器
- 实时更新队列显示，反映真实状态

src/views/LibraryView.vue

@@ -1893,12 +1893,13 @@ async function batchDeepScan() {
   const immediateCount = Math.min(filesToProcess.length, maxConcurrent)
   const queueTotal = Math.max(0, filesToProcess.length - maxConcurrent)
   
-  actionMsg.value = `Starting: ${immediateCount} immediate, ${queueTotal} queuing...`
+  let processing = 0
-  
   let successCount = 0
   let failCount = 0
   
-  const tasks = filesToProcess.map((f, index) => {
+  actionMsg.value = `Starting: ${immediateCount} immediate, ${queueTotal} queuing...`
+  
+  const tasks = filesToProcess.map((f) => {
     return limit(async () => {
       const fileUuid = f.file_uuid
       if (!fileUuid) {
@@ -1906,19 +1907,20 @@ async function batchDeepScan() {
         return
       }
       
-      const position = index + 1
+      processing++
-      const queuePosition = position - maxConcurrent
+      const queueCount = Math.max(0, filesToProcess.length - successCount - failCount - processing)
       
-      if (queuePosition > 0) {
+      if (queueCount > 0) {
-        actionMsg.value = `Processing ${successCount + 1}/${filesToProcess.length} (${queuePosition} queuing)...`
+        actionMsg.value = `Processing ${successCount + 1}/${filesToProcess.length} (${queueCount} queuing)...`
       } else {
-        actionMsg.value = `Processing ${position}/${filesToProcess.length}...`
+        actionMsg.value = `Processing ${successCount + 1}/${filesToProcess.length}...`
       }
       
       try {
         const file = filesCache.value.find((x: any) => x.file_uuid === fileUuid)
         if (!file) {
           failCount++
+          processing--
           return
         }
         
@@ -1940,6 +1942,8 @@ async function batchDeepScan() {
       } catch (e: any) {
         failCount++
         console.error('[batchDeepScan] Failed:', f.file_name, e)
+      } finally {
+        processing--
       }
     })
   })