Add chunked uploads and raise storage rate to GHS 0.30/GB/month.

Large files upload in 5 MB chunks (hosting file manager pattern) for the
transfer UI and Ladill Mail S2S API, with no app-level file size cap when
TRANSFER_MAX_FILE_BYTES=0.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Http/Controllers/Transfer/OverviewController.php

@@ -61,7 +61,7 @@ class OverviewController extends Controller
         }
 
         $storageGb = round($storageBytes / (1024 * 1024 * 1024), 2);
-        $monthlyEstimateGhs = round($storageGb * (float) config('transfer.price_per_gb_month', 0.15), 2);
+        $monthlyEstimateGhs = round($storageGb * (float) config('transfer.price_per_gb_month', 0.30), 2);
 
         return view('transfer.dashboard', [
             'activeCount' => $activeCount,