Add AI SBOM object definitions for model, dataset, compute, governance, and top-level SBOM

[adulau]

Motivation

• Introduce structured metadata objects to represent AI SBOM elements following the BSI "SBOM for AI — minimum elements" reference.
• Provide first-class object definitions for model, dataset, compute/runtime, governance artifacts, and top-level SBOM metadata to support AI supply-chain reporting and analysis.

Description

• Added objects/ai-sbom/definition.json containing top-level SBOM attributes such as sbom-id, ai-system-name, timestamp, author, supplier, and standard with required fields and UUID.
• Added objects/ai-model-component/definition.json for model metadata including model-name, model-version, model-identifier, artifact-hash, model-type, provider, and training-framework with required fields and UUID.
• Added objects/ai-dataset-component/definition.json for dataset metadata including dataset-name, dataset-version, dataset-identifier, dataset-license, dataset-origin, data-sensitivity, and integrity-hash with required fields and UUID.
• Added objects/ai-compute-component/definition.json and objects/ai-governance-component/definition.json for compute/runtime and governance artifacts respectively, each declaring relevant attributes (e.g., component-name, component-type, document-name, document-type, document-link) and UUIDs.

Testing

• No automated tests were run for this change.

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Codex Task