Add approval-gated cross-repository dependency publication orchestrator

[leehack]

Priority

P1 - the current owning-repository schedules can publish independently, which conflicts with the approved single approval boundary and can produce partially coordinated dependency state.

Evidence

• llamadart-native and litert-lm-native scheduled workflows currently dispatch publishing workflows directly.
• llama-web-bridge scheduled automation currently couples dependency movement to a bridge pin PR.
• A repository-scoped GITHUB_TOKEN cannot dispatch and correlate workflows across the owning repositories.
• llamadart issue Support semantic-version llamadart-native tags in pin synchronization and consumption #393 establishes the consumer tag/provenance contract but intentionally does not broaden into release orchestration.

Required design

Scheduled work is detection/preparation only. Publication starts only from an explicitly approved llamadart workflow and results in one combined downstream pin-upgrade PR after every owning release and consumer smoke passes.

Acceptance criteria

• Add a scheduled read-only scan that records exact native, Web, and LiteRT candidate versions/source commits without publishing or changing pins.
• Add an explicit workflow_dispatch protected by a required-approval environment.
• Dispatch each owning build/publish workflow with exact source refs, target tags, and a shared correlation identifier.
• Bind verification to exact workflow run IDs and head SHAs; fail closed on ambiguity, timeout, cancellation, or partial success.
• Verify manifests/provenance, GitHub digests, checksum files, required bundles, and owning-repository smokes.
• Run the representative llamadart native, Web worker/WASM, and LiteRT consumer smokes against the published artifacts.
• Open one combined llamadart pin-upgrade PR only after all gates pass; include native headers/bindings, Web assets tag, LiteRT pins, maintained docs, support matrix, and changelog as applicable.
• Make retries idempotent and concurrency-safe, and publish an auditable summary without logging tokens or signed URLs.
• Use a least-privilege GitHub App or fine-grained credential; document permissions, rotation, and protected-environment ownership.
• Keep owner source changes in their own repositories and PRs; dependency publication alone must not require companion pin PRs.

Out of scope

Publishing from the scheduled scan, changing owner source, merging pin PRs, or releasing llamadart automatically.