fix: FilesView merge logic and computed property

Bug: When regFiles API fails, all files get 'unregistered' status even if
they are actually registered. Also, computed property was using reference
to files.value instead of a copy, which could cause mutation issues.

Fix:
- Fetch scan results FIRST (source of truth for files on disk)
- Use scan API's is_registered field as fallback status
- Only override with regFiles data if file exists in scan results
- Computed property now uses [...files.value] to create a copy
- Skip files from regFiles that don't exist on disk (deleted)

portal/src/views/FilesView.vue

@@ -220,7 +220,8 @@ function getMediaType(fileName: string): 'video' | 'photo' {
 }
 
 const displayFiles = computed(() => {
-  let result = files.value
+  // Start with a copy to avoid mutation issues
+  let result = [...files.value]
   
   // Filter by media type
   if (mediaType.value !== 'all') {
@@ -263,7 +264,20 @@ async function fetchFiles() {
   try {
     const config = getCurrentConfig()
     
-    // Get registered files with real processing status FIRST
+    // Get scan results FIRST (source of truth for files on disk)
+    const scanResp = await httpFetch<any>(`${config.api_base_url}/api/v1/files/scan`)
+    const scanFiles: any[] = (scanResp?.files || []).map((f: any) => {
+      const mediaType = getMediaType(f.file_name)
+      return {
+        ...f,
+        media_type: mediaType,
+        is_indexed: false,
+        // Use scan API's is_registered field as default status
+        status: f.is_registered ? 'pending' : 'unregistered'
+      }
+    })
+
+    // Get registered files with real processing status
     let regFiles: any[] = []
     try {
       const regResp = await httpFetch<any>(`${config.api_base_url}/api/v1/files?page=1&page_size=200`)
@@ -277,38 +291,37 @@ async function fetchFiles() {
         }
       })
     } catch {
-      // Registered files API may not be available
+      // Registered files API may not be available; scan data will be used as fallback
+      console.warn('Failed to fetch registered files, using scan data as fallback')
     }
 
-    // Get scan results
-    const scanResp = await httpFetch<any>(`${config.api_base_url}/api/v1/files/scan`)
-    const scanFiles: any[] = (scanResp?.files || []).map((f: any) => {
-      const mediaType = getMediaType(f.file_name)
-      return {
-        ...f,
-        media_type: mediaType,
-        is_indexed: false
-      }
-    })
-
-    // Build a set of registered file paths for quick lookup
-    const registeredPaths = new Set(regFiles.map(f => f.file_path))
+    // Build a map of registered files by file_path for quick lookup
+    const regMap = new Map<string, any>()
+    for (const f of regFiles) {
+      regMap.set(f.file_path, f)
+    }
 
     // Merge: start with scan results, override with registered data where available
     const merged = new Map<string, any>()
     
     // First pass: add all scan results
     for (const f of scanFiles) {
-      const isRegistered = registeredPaths.has(f.file_path)
-      merged.set(f.file_path, {
-        ...f,
-        status: isRegistered ? 'pending' : 'unregistered'
-      })
+      merged.set(f.file_path, { ...f })
     }
     
-    // Second pass: override with real registered data
+    // Second pass: override with real registered data (only for files that exist in scan)
     for (const f of regFiles) {
-      merged.set(f.file_path, f)
+      if (merged.has(f.file_path)) {
+        // File exists on disk, update with real status
+        const existing = merged.get(f.file_path)
+        merged.set(f.file_path, {
+          ...existing,
+          ...f,
+          media_type: f.media_type || existing.media_type,
+          is_indexed: f.is_indexed || existing.is_indexed
+        })
+      }
+      // If file not in scan, it might have been deleted from disk - skip it
     }
 
     files.value = Array.from(merged.values())