Introduced a UsernameValidator with Cyrillic and length checks, integrated into AuthService and registration flow. Added InvalidUsernameException and related interface. Updated User model to support friend requests, added FriendsController (stub), and configured Friendship entity in EF Core. Adjusted UserValidator max name length and removed navigation properties from PrivateChat.
Introduces Friendship and PrivateChat models, repository interfaces, and implementations for managing friendships. Adds validators and comprehensive unit and integration tests for friendship logic. Updates InviteUserController with new endpoints and restricts access to admin role. Removes unnecessary project references from Govor.API.csproj and registers new DbSets in GovorDbContext.
Artemy