Fix FilePond: maxFileSize as bytes + temp files survive page reload

1. maxFileSize bug: FileValidateSize plugin overrides core's maxFileSize
   setter. Core uses toBytes('1GB') = 1073741824, but plugin registers
   maxFileSize as [null, Type.INT] which calls toInt('1GB') = 1.
   Fix: all maxFileSize and perExtensionMaxSize values as raw bytes.
   Also fix option name: fileValidateSizeFilterItem → fileValidateSizeFilter.

2. Temp file persistence: files uploaded via FilePond went to
   tmp/filepond/ and vanished from the UI on page reload because
   data-existing-files only included DB-persisted files.
   Fix: session-track temp file_ids in handleProcess, inject via
   getSessionTempFiles() into data-existing-files, teach handleLoad
   to stream temp files from disk, and route JS remove → revert for hex IDs.

app/public/admin/fragments/fichiers.php

@@ -45,6 +45,14 @@ if ($thesisId) {
                 ],
             ];
         }
+
+        // Include session temp files so uploads survive page reload
+        require_once APP_ROOT . '/src/FilepondHandler.php';
+        $tempFiles = FilepondHandler::getSessionTempFiles($queueType);
+        foreach ($tempFiles as $tf) {
+            $result[] = $tf;
+        }
+
         return $result;
     };