Configurable cache nginx upload limit in Helm chart

The Tuist Helm chart now exposes a configurable cache.nginx.clientMaxBodySize value for the cache nginx sidecar, rendered as client_max_body_size in the generated nginx configuration. This keeps nginx aligned with the cache application’s module part size limit and prevents 413 Request Entity Too Large errors during Remote Cache module uploads. The upload proxy paths also disable request buffering so parts stream through to the cache application. The chart README documents the new value.