Port over Jeremy's fix for slow uploads

ref: https://fizzy.37signals.com/5986089/collections/7/cards/944

lib/rails_ext/active_storage_blob_service_url_for_direct_upload_expiry.rb

@@ -0,0 +1,23 @@
+#
+#  see https://github.com/basecamp/haystack/pull/7862
+#
+module ActiveStorage
+  mattr_accessor :service_urls_for_direct_uploads_expire_in, default: 48.hours
+end
+
+module ActiveStorageBlobServiceUrlForDirectUploadExpiry
+  # Override default expires_in to accommodate long upload URL expiry
+  # without having to lengthen download URL expiry.
+  #
+  # Accounts for Cloudflare only proxying slow client uploads once they're
+  # fully buffered, long after the URL expired.
+  #
+  # 48 hours covers a 10GB upload at 0.5Mbps.
+  def service_url_for_direct_upload(expires_in: ActiveStorage.service_urls_for_direct_uploads_expire_in)
+    super
+  end
+end
+
+ActiveSupport.on_load :active_storage_blob do
+  prepend ::ActiveStorageBlobServiceUrlForDirectUploadExpiry
+end