- Updated `new-api` skill `SKILL.md` to document the centralized v1.go route registration and domain-driven sub-routing patterns
- Updated `AGENTS.md` instructions with the new router subpackages (`root`, `v1`) and route file layout guidelines
- Created `internal/router/v1` subpackage
- Split routes into `admin.go`, `user.go`, `public.go`, and `custom.go`
- Cleaned up imports and helper registration functions from `router.go`
- Removed obsolete `internal/router/custom.go`