feat: Initialize kubebuilder project structure

[kitsunoff]

⚠️ TDD MANDATORY

Tests MUST be written BEFORE implementation code. No exceptions.

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Description

Initialize the kubebuilder project with proper structure for NixOS Operator migration.

Tasks

• Write tests for project initialization validation
• Run kubebuilder init --domain homystack.com --repo github.com/homystack/nixos-operator
• Create Machine API with kubebuilder create api --group nio --version v1alpha1 --kind Machine
• Create NixosConfiguration API with kubebuilder create api --group nio --version v1alpha1 --kind NixosConfiguration
• Setup project structure following kubebuilder conventions
• Configure Makefile for build/test/deploy
• Verify all tests pass

Reference

See docs/kubebuilder-migration-analysis.md sections 1-3 for current structure and CRD definitions.