feat(jobs): expose ash/ocr hex on awaiting_signature JobStatus result

[TaprootFreak]

Why

A pure-TypeScript wallet (@zkcoins/sdk) needs account_state_hash (ash) + output_coins_root (ocr) to sign the send commitment. Until now the awaiting_signature JobStatus carried only proof_id; ash/ocr were reachable solely via GET /api/proof/{id} as a binary bincode CoinProof blob that only Rust/wasm can decode. That breaks the thin-client rule (wallet = key only, trusts the node, no heavy client-side logic; see CONTRIBUTING "Trust model").

What

When a send job transitions to awaiting_signature, ash + ocr are written as lowercase hex into the job result, so GET /api/jobs/:id and the SSE stream surface them under result.account_state_hash / result.output_coins_root — the exact keys the SDK's pay() already reads. This closes the pure-TS commit loop without any binary proof decode.

Where ash/ocr come from

The same source the completed mint/commit results use: ProofData::from_field_elements over the send proof's public inputs, hex-encoded via digest_to_bytes. Extraction is factored into a shared flow::send_commit_hashes helper that mint_flow, send_flow, and commit_flow all call, so the hex is bit-identical to what createCommitment expects and commit_flow re-derives from the same proof.

Additive / minimal

• completed result shape, top-level proof_id, and the JobStatusResponse wire schema (result is already free-form JSON) are unchanged.
• No new endpoint, env var, or migration.
• set_awaiting_signature stores the result in the existing response_body column (the terminal complete body overwrites it later). The GET handler and SSE initial frame now surface result for awaiting_signature in addition to completed; a post-restart resume re-publishes the persisted hashes.

Tests / gates

• api_remote send roundtrip now asserts the awaiting_signature result hex equals the proof-decoded ash/ocr (contract check; runs in deploy-dev / ci:full).
• job_store + router unit tests cover the new persistence + snapshot paths.
• Local coverage gate green: 100% lines + 100% functions on the node package (442 tests passed), cargo fmt --check, clippy (MVP + all-features) -D warnings, and cargo check --workspace --all-features all clean.