Make NAS the primary storage when enabled (not a mirror)

When NAS sync is enabled:
- Audio uploads: pushed to NAS via NasSyncVideoJob, local file deleted immediately after
- Video uploads: processed locally (ffprobe, compress, HLS), then at the end of
  GenerateHlsJob the final compressed file is re-synced to NAS and the local copy removed
- stream() and download(): if local file is missing, pull from NAS into a local
  stream cache (storage/app/nas_cache/videos/) and serve from there with full
  byte-range support — so seeking still works over NAS-sourced files

When NAS is disabled:
- Upload, stream, and download all use local storage exclusively (no change)

HLS segments are intentionally kept local: they are small, generated on-demand,
and serving them via per-segment SMB round-trips would hurt playback performance.

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

app/Jobs/NasSyncVideoJob.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Jobs;
+
+use App\Models\Video;
+use App\Services\NasSyncService;
+use Illuminate\Bus\Queueable;
+use Illuminate\Contracts\Queue\ShouldQueue;
+use Illuminate\Foundation\Bus\Dispatchable;
+use Illuminate\Queue\InteractsWithQueue;
+use Illuminate\Queue\SerializesModels;
+
+class NasSyncVideoJob implements ShouldQueue
+{
+    use Dispatchable, InteractsWithQueue, Queueable, SerializesModels;
+
+    public int $tries   = 3;
+    public int $backoff = 60;
+
+    public function __construct(public readonly Video $video) {}
+
+    public function handle(NasSyncService $nas): void
+    {
+        if (! $nas->isEnabled()) return;
+        try {
+            $nas->syncVideo($this->video);
+
+            // Audio/music uploads have no further processing jobs, so it's safe
+            // to remove the local file immediately after a successful NAS push.
+            // Video uploads must keep the local file until GenerateHlsJob finishes.
+            if ($this->video->type === 'music') {
+                $nas->deleteLocalVideo($this->video);
+            }
+        } catch (\Throwable $e) {
+            \Illuminate\Support\Facades\Log::warning('NAS syncVideo failed for video ' . $this->video->id . ': ' . $e->getMessage());
+        }
+    }
+}