Introduce support for grouping multiple sequential file uploads into a single box using the `X-Warpbox-Batch` header. This is particularly useful for ShareX multi-file selections, which are sent as separate back-to-back requests.
Additionally, this change:
- Updates the ShareX configuration template to opt-in to batching by default.
- Switches ShareX configuration placeholders to the modern `{json:...}` format.
- Adds `thumbnailUrl` to the upload response schema and documents its usage.
Daniel Legt
adb1a12dfd