Added JSON tags to the User struct to match frontend expectations and excluded sensitive fields. Updated session management to include and persist DisplayName. Unified user field names (using display_name) across backend, sessions, and frontend UI.
Restored 'admin123' as the default password in db init and added a -reset-admin flag to main.go.
This commit replaces the Axum/Rust backend with a Gin/Go implementation. The original Rust code has been archived in the 'rust' branch.
