Integrate Context Builder with Prompt SDK v1 and downstream handoff

[andrewperis]

Parent epic: #5

Summary

Integrate Context Builder with Prompt SDK v1 and downstream handoff for Context Builder v1.

Ownership and dependencies

• Repositories: platform.
• Depends on: Implement Context Builder provenance, redaction and audit handoff #82.
• Baseline: released Prompt SDK v1.0.0 and Context Package v1.0.0; do not change immutable contract bytes.

Scope and deliverables

• Implement a typed/validated build → review/authorization handoff → bind/render → mock execute flow using the immutable released Prompt SDK contracts.
• Obtain the separate matching package-instance authorization from an approved provider, never synthesize production approval inside the builder.
• Expose prepared package/reference, safe evidence and explicit failures for future Comic Manifest/Build Orchestrator consumers without implementing those epics.
• Document mismatch, stale package, undeclared slot, classification ceiling and cancellation/failure behavior across the boundary.

Acceptance criteria

• Synthetic text/structured prompt examples consume genuinely built packages, not only hand-authored mocks.
• Invalid or unauthorized packages cannot reach rendering/provider execution; tests assert non-invocation.
• Execution provenance links back to the expected package/build/correlation identities.
• No canon/lore retrieval is added to Prompt SDK and no downstream orchestration/release authority is assumed.

Implementation guardrails

Follow Constitution v1.0.0 at a9cc8a503aa30e17820edc62ac95f7cbe10e0564 and repository boundaries. Add focused tests with implementation; the suite task consolidates rather than postpones testing. Public issues, fixtures and docs use synthetic/already-public material only. Approved private inputs stay behind explicit secure artifact boundaries. No direct Lore checkout, silent declassification, self-approval or canon promotion.