aisman

Direct session 23, Step 1: Remove blob-based avatar and logo storage from database:
- SQL migration script: drop AspNetUsers.AvatarData and Org.OrgLogoData
- Remove AvatarData property from ApplicationUser model
- Remove OrgLogoData property from Org model
- Rewrite AccountController avatar to use filesystem
- Remove OrgLogoData legacy fallback from OrgsController
- Update Razor pages avatar check to use AvatarImgType
- Update DB table definition files to remove blob columns