- Add tsidp target to build_docker.sh for standard Tailscale image builds
- Add publishdevtsidp Makefile target for development image publishing
- Remove Dockerfile, using standard build process
- Include tsidp in depaware dependency tracking
- Update README with comprehensive Docker usage examples
This enables tsidp to be built and published like other Tailscale components
(tailscale/tailscale, tailscale/k8s-operator, tailscale/k8s-nameserver).
Fixes#16077
Signed-off-by: Raj Singh <raj@tailscale.com>