Address→Hex Lookup: Slice 3 — global hold KV store + /api/holds (exclusive, email, 30d expiry)

[tylermalin]

Part of Address → Hex Lookup & Reserve (Res 4) — see docs/prd/address-hex-lookup.md. The core new primitive.

Goal: Off-chain exclusive reservations for Res-4 cells outside the curated 200. No mint, no Genesis edition consumed.

Build

• New apps/web/src/lib/global-hold-store.ts mirroring genesis-claim-registry.ts, separate KV namespace (hold:res4:<hexId>, hold:email:<email>, hold:index).
• POST/GET/DELETE /api/holds: exclusive set-if-absent lock, email-anchored, expiresAt = heldAt + 30d, lazy reclaim on read.

Hard invariants

• Never increments genesis:issued; never calls issueClaim or the contract.
• Stores canonical Res-4 hexId + email (+ referrerId) so a future global-res change can fractionalize via cellToChildren.

TDD anchor: exclusive lock under concurrent holds; expiry reclaim; cap-isolation (asserts genesis:issued untouched).