feat: add aks command

[TacoRocket]

Summary

• add the Phase 3 aks command with cluster endpoint, identity context, auth posture, and network shape
• intentionally merge the new README logo placement and supported-command refresh with this slice
• add fixture, schema, golden, help, API-mapping, and terminal UX coverage for AKS

Validation

• PYTHONPATH=src python3 scripts/generate_schemas.py
• python3 -m ruff check src tests scripts
• PYTHONPATH=src python3 -m pytest tests/test_collectors.py tests/test_golden_outputs.py tests/test_contract_schemas.py tests/test_cli_smoke.py tests/test_help.py tests/test_terminal_ux.py tests/test_models.py
• PYTHONPATH=src python3 -m pytest