Compose contract drafter with canonical send-as

[RYDE-PLAY]

Summary:

• enforce contract drafting with deterministic template reconciliation and a typed runx.contract_draft.v1 packet
• consume immutable first-party runx/send-as@sha-1f90b9364a3a#plan and re-export its validated plan without any provider delivery runner
• materialize the official plan-only package for legacy registry resolvers while preserving the canonical package identity and schemas
• refuse incomplete or unreconciled requests; missing required terms emit neither a draft nor a proposal

Verification:

• pnpm dlx @runxhq/cli@0.8.2 harness ./skills/contract-drafter --json (4/4)
• cargo run --manifest-path crates/Cargo.toml -q -p runx-cli -- harness ./skills/contract-drafter --json (4/4)
• node scripts/audit-core-skills.mjs --check --json (passed, 0 findings)
• pnpm verify:fast (all required steps passed)
• isolated old-protocol local registry publish and pre-publish harness (4/4)