time-locked-attestations v0.3: §9 future-work tracking

[proofmancer]

Tracks the §9 future-work surface from time-locked-attestations v0.2.

• ZK-friendly variant (§9.1) — SNARK-based reveal lets chain verify "committed payload satisfies predicate P" without learning payload. Applications: sealed-bid auctions, regulatory filings. Poseidon hash option exists in §3.4; v0.2 specifies cleartext-reveal only.
• Cross-chain time-locks (§9.2) — reveal gated by foreign-chain block height. IBC light-client proof of foreign height. Cascade interaction with cross-schema-composition §3.4. Candidate for unified cross-chain follow-up paper.
• VDF-based hard time-locks (§9.3) — committer cannot reveal before T VDF steps. Trustless time-lock (no chain consensus). Different security model. Positioned as complement, not competitor (§7).
• Multi-party commit-reveal (§9.4) — M-of-N reveal pattern for escrow agents, multi-stakeholder embargos. Requires threshold-signing the reveal OR Shamir-style secret-sharing of payload+nonce.

Authoring trigger

§6.1 gate: design-partner use-case submissions matching the §6.2 template (auction / embargo / regulatory). At least one per category before v0.3 work opens.