Covers: snake_case param renames, mutex RLock/Unlock mismatches, user.Hubs keyed by hub.Id, hub color using new_name, DELETE params sent as query, delete(target.Hubs, hub.Id), root/member role Id swap, and the three new PATCH
/hub/channel/roles/* handlers.
- replace UserSetColor/UserSetPronouns with single UserUpdateProfile that dynamically builds one UPDATE query from UserProfileUpdateList
- add getConnectionWithResponseOnFail helper to deduplicate connection ID parsing and validation across handlers
- rename file.go to attachmentFile.go and update handler names
- GetDownloadUrlAndMetadata now fetches object metadata via StatObject and returns it alongside the presigned URL
- file download endpoint returns JSON with url and originalName
- add description field to user and DB schema
- remove unused ConnectionState variants (GroupFellow, GroupFriend)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>