Add Zapier interface simulator, tree-node Merkle lookups, and user docs

In-process trace console validates hops, faults, recoveries, and
suggested changes before zapier-platform push. User guide covers
signup through central-chain and bulk-summary tree-node hash lookup.

packages/zapier-user-docs/08-bulk-merkle-summaries.md

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+# 8. Bulk Merkle summaries
+
+**Create Batch Timestamps** takes one payload per line (or an `items[]` array).
+
+Middleware:
+
+1. SHA-256 each item (leaf).
+2. Build a Merkle tree.
+3. Seal **only the root** on the main Verae chain (one certificate, one `jobId`).
+4. Put each leaf’s **inclusion proof** on a sharded **tree-node** archive (`kind: tree`).
+5. Return `jobId`, `merkleRoot`, `leafCount`, and the leaf hashes.
+
+Those member hashes are **not individually itemized** on the main chain. Looking them up with **Find Timestamp by SHA256** returns empty. That is expected.
+
+Why batch: one chain write for thousands of documents, cheaper and faster, while each document can still prove inclusion later via its proof + the root certificate.
+
+Simulator: scenario **Batch Merkle**, then copy the first leaf into the SHA256 field.