simplify: dedupe boilerplate and remove dead code across all layers

lib/widget/file_pick.dart

@@ -17,7 +17,6 @@ class FilePick {
 
   static Future<List<String>?> documentPick() async {
     final result = await FilePicker.pickFiles(allowMultiple: true);
-    final paths = result?.files.nonNulls.map((e) => e.path).toList();
-    return paths?.nonNulls.toList();
+    return result?.files.map((e) => e.path).nonNulls.toList();
   }
 }