Add embedded runtime smoke test (scripts/ci/embedded_smoke.sh)

[enricopiovesan]

Summary

Add CI smoke test proving embedded runtime path: bundled manifest → in-process execute → multi-capability workflow completes.

Why

Phase 1 phase1_smoke.sh targets HTTP sidecar only. Phase 3 needs a parallel gate.

Depends on

• Embeddable host SDK landed in Traverse
• At least one platform client migrated

Blocked by

• Traverse #553
• Platform migration tickets

Definition of Done

• scripts/ci/embedded_smoke.sh exists; exit 0 on pass
• Documented in docs/embedded-runtime-plan.md validation section
• Wired into CI when native embedded host available in CI agents

Validation

bash scripts/ci/embedded_smoke.sh