Added critical attributes to both upload endpoints to properly handle
large multipart file uploads from the editor:

1. [Consumes("multipart/form-data")]
   - Explicitly declares the endpoint accepts multipart form data
   - Helps ASP.NET Core routing and model binding understand the content type
   - Improves API documentation in Swagger

2. [DisableRequestSizeLimit]
   - Removes the default 30MB request size limit
   - Allows uploading large game asset packages without size restrictions
   - Essential for editor uploads which can contain hundreds of MB of assets

3. [RequestFormLimits(MultipartBodyLengthLimit = long.MaxValue, ValueLengthLimit = int.MaxValue)]
   - Removes limits on multipart body length and individual value length
   - Prevents HTTP 400 errors from default ASP.NET Core form size limits
   - Allows batched uploads of many files at once

Also added:
- using Microsoft.AspNetCore.Http.Features; for RequestFormLimits attribute

Without these attributes, ASP.NET Core's default FormOptions would reject
requests that exceed the built-in limits, resulting in HTTP 400 Bad Request
errors before the controller method is even reached.

These changes complement the previous fix that changed [FromForm] to
[FromQuery] for the subfolder parameter.