Update `createOrAppendBox` to accept the upload policy and admin status, allowing policy enforcement to be handled during the box creation/append decision process. This ensures that appending files to an existing batch does not incorrectly trigger daily or active box creation limits, as no new box is being created.
Also, add unit tests to verify that batched uploads successfully bypass both daily and active box creation caps.
- Optimize the ban matching middleware by using a read-only transaction (`db.View`) for the initial scan, avoiding the single bbolt write lock on every request when no ban matches.
- Implement periodic pruning of stale entries in the upload grouper map to prevent unbounded memory growth over time.
- Avoid redundant parsing of the `max_days` form value in the upload handler.
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.
