Afia: fix transfer chat context querying nonexistent download_count

context() selected/used download_count on the transfers table, but the
column is downloads_total (see model + migration) — every Afia chat 500'd
with 'could not respond' before reaching the LLM. Use downloads_total.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/Http/Controllers/Qr/AfiaController.php

@@ -86,14 +86,14 @@ class AfiaController extends Controller
             ->with('qrCode:id,short_code')
             ->latest()
             ->limit(3)
-            ->get(['id', 'title', 'qr_code_id', 'download_count', 'expires_at']);
+            ->get(['id', 'title', 'qr_code_id', 'downloads_total', 'expires_at']);
 
         if ($recent->isNotEmpty()) {
             $ctx['recent_transfers'] = $recent->map(fn (Transfer $transfer): string => sprintf(
                 '%s (%s, %d downloads%s)',
                 $transfer->title,
                 $transfer->qrCode?->short_code ?? 'no QR',
-                $transfer->download_count,
+                $transfer->downloads_total,
                 $transfer->expires_at ? ', expires '.$transfer->expires_at->toDateString() : '',
             ))->implode('; ');
         }