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/Api/TransferController.php

@@ -23,8 +23,12 @@ class TransferController extends Controller
             return response()->json(['message' => 'Forbidden.'], 403);
         }
 
-        $maxKb = (int) ceil(((int) config('transfer.max_file_bytes', 524288000)) / 1024);
+        $maxBytes = (int) config('transfer.max_file_bytes', 0);
         $maxFiles = (int) config('transfer.max_files_per_transfer', 20);
+        $fileRules = ['required', 'file'];
+        if ($maxBytes > 0) {
+            $fileRules[] = 'max:'.(int) ceil($maxBytes / 1024);
+        }
 
         $data = $request->validate([
             'mailbox' => ['required', 'email', 'max:255'],
@@ -32,7 +36,7 @@ class TransferController extends Controller
             'message' => ['nullable', 'string', 'max:2000'],
             'retention_days' => ['nullable', 'integer', 'min:1', 'max:365'],
             'files' => ['required', 'array', 'min:1', 'max:'.$maxFiles],
-            'files.*' => ['required', 'file', 'max:'.$maxKb],
+            'files.*' => $fileRules,
         ]);
 
         try {