Enable folder upload for group event photos

Add a folder upload capability to the photo upload feature — allowing users to select and upload an entire folder of images in a single action, mirroring the experience available in tools like Google Drive and SharePoint.

Leads regularly handle post-event photo albums containing 50–200+ images. Removing the friction of individual uploads would meaningfully reduce administrative burden and encourage timely, consistent documentation of BRG events — supporting inclusion initiatives across the organization.