Use NAS as primary storage — direct upload when enabled

When NAS storage is enabled, uploaded files go directly to the NAS share
(users/{username}/videos/{title-slug}/) with no permanent local copy kept.
Thumbnails and video are fetched from NAS on demand for streaming/playback.
When NAS is disabled, files are organised into the same directory schema
in local storage.

- VideoController: branch upload flow on NAS enabled/disabled
- NasSyncService: add uploadDirectToNas() for direct NAS writes,
  organizeLocalFiles() for local NAS-schema, localVideoDir() resolver,
  deleteLocalAssets() for post-sync cleanup
- GenerateHlsJob: download from NAS via ensureLocalCopy() when local
  file is absent (NAS-primary mode); clean up temp after HLS generation
- CompressVideoJob: place compressed file alongside original (any dir)
- Video/VideoSlide models: localVideoPath(), localThumbnailPath(),
  thumbnailStorageKey(), localPath(), storageKey() helpers for
  format-agnostic path resolution (old flat paths + new NAS-schema paths)
- MediaController: serve thumbnails from NAS-mirrored paths with NAS fallback
- SuperAdminController: use model path helpers for file deletion
- NasFreeLocalStorage: scan new users/ tree in addition to legacy flat dirs
- Settings: rename "NAS Storage Sync" tab to "NAS Storage", update description

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

app/Models/Video.php

@@ -69,19 +69,53 @@ class Video extends Model
         return $this->slides()->count() > 1;
     }
 
+    // ── Local filesystem path helpers ─────────────────────────────────────────
+
+    /**
+     * Absolute path to the video file on local disk.
+     * Works for both old flat paths ("public/videos/…") and new NAS-mirrored paths ("users/…").
+     */
+    public function localVideoPath(): string
+    {
+        return storage_path('app/' . $this->path);
+    }
+
+    /**
+     * Absolute path to the thumbnail on local disk.
+     * Old format: storage/app/public/thumbnails/{filename}
+     * New format: storage/app/{relative-path}  (path contains a slash, e.g. users/…/thumb.jpg)
+     */
+    public function localThumbnailPath(): ?string
+    {
+        if (! $this->thumbnail) return null;
+        return str_contains($this->thumbnail, '/')
+            ? storage_path('app/' . $this->thumbnail)
+            : storage_path('app/public/thumbnails/' . $this->thumbnail);
+    }
+
+    /**
+     * Storage::delete()-compatible key for the thumbnail.
+     */
+    public function thumbnailStorageKey(): ?string
+    {
+        if (! $this->thumbnail) return null;
+        return str_contains($this->thumbnail, '/')
+            ? $this->thumbnail
+            : 'public/thumbnails/' . $this->thumbnail;
+    }
+
     // Accessors
     public function getUrlAttribute()
     {
         return asset('storage/videos/'.$this->filename);
     }
 
-    public function getThumbnailUrlAttribute()
+    public function getThumbnailUrlAttribute(): ?string
     {
         if ($this->thumbnail) {
-            return asset('storage/thumbnails/'.$this->thumbnail);
+            return route('media.thumbnail', $this->thumbnail);
         }
 
-        // Return null when no thumbnail - social platforms will use their own preview
         return null;
     }