QVAC-23762 expose metadata-aware AudioGen caption conditioning

[freddy311082]

Summary

• expose augmentCaptionWithMetadata through AudioGen's public TypeScript API and native addon
• validate and forward the option through the SDK streaming contract
• pin the AudioGen package to the QVAC-23762 registry baseline

Test plan

• Build the native macOS addon against the finalized registry port
• Run AudioGen type and generated-file checks
• Run AudioGen unit tests (115/115)
• Run SDK typecheck and AudioGen schema tests
• Regenerate and verify the SDK contract

Dependencies

• Depends on QVAC-23762 bump speech-cpp for metadata-aware caption conditioning qvac-registry-vcpkg#319.
• Stacked on QVAC-22883/audiogen-repaint-flow-edit until the parent AudioGen changes land in the monorepo base.

[github-actions]

License compliance — clean

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NOTICE presence (advisory)

Missing NOTICE (advisory, does not block):

• ./.github/actions/release-merge-guard
• ./docs/website
• ./packages/ggml-coload-smoke
• ./packages/fabric/test/integration
• ./packages/inference-addon-cpp/mobile
• ./packages/sdk/e2e
• ./packages/llm-llamacpp/benchmarks/performance
• ./packages/llm-llamacpp/benchmarks/server
• ./packages/vla-ggml/sim/server
• ./packages/embed-llamacpp/benchmarks/performance
• ./packages/embed-llamacpp/benchmarks/server
• ./packages/asr-ggml/benchmarks/server

[freddy311082]

Unnecessary PR opned by the AI, not by me