Add multi-architecture build support

[daniil-nedostup]

Is your feature request related to a problem? Please describe.
Currently, the operator supports building a single Go binary by customizing GOOS and GOARCH, which works well for targeting a specific platform. However, there is no built-in support for building and packaging binaries for multiple architectures into a single Docker image. As a result, it is not possible to produce and publish a multi-architecture Docker image (e.g., one supporting both amd64 and arm64) using the current Makefile and Dockerfile setup.

Describe the solution you'd like
Native support for building multi-architecture Docker images. This would involve extending the Dockerfile and/or Makefile to support injecting multiple platform-specific Go binaries and producing a manifest list that references architecture-specific images under a unified image tag.

Describe alternatives you've considered
Building and pushing separate architecture-specific images manually, but this approach lacks automation and consistency.

Additional context
This enhancement would improve compatibility with heterogeneous Kubernetes clusters and edge environments where arm64 support is required. It would also align with current best practices in container image publishing by enabling unified multi-architecture images.