docs(receipt-cli): add an offline quick start (#321) (#336)

Co-authored-by: emrekayat <237104270+emrekayat@users.noreply.github.com>

Author: emrekayat

services/receipt-cli/README.md

@@ -0,0 +1,75 @@
+<!-- SPDX-License-Identifier: MIT -->
+# Receipt CLI
+
+Export a round receipt from Soroban RPC, verify a receipt offline, or create a
+redacted copy for a public demo. See the canonical [receipt format and verification
+guide](../../docs/RECEIPTS.md) for the schema and verification guarantees.
+
+Run the following commands from the repository root after `pnpm install`.
+The CLI command runs inside `services/receipt-cli`, so relative file paths below
+are relative to that workspace.
+
+## Offline verification
+
+Verify the committed golden fixture without a wallet or network access:
+
+```sh
+pnpm --filter @sub-rosa/receipt-cli receipt verify src/fixtures/golden.json
+```
+
+Request machine-readable output:
+
+```sh
+pnpm --filter @sub-rosa/receipt-cli receipt verify src/fixtures/golden.json --json
+```
+
+JSON output includes `valid`, `receiptId`, `roundId`, `checkedAt`, `errors`, and
+`warnings`. Successful verification exits with code 0; invalid receipts, unreadable
+files, malformed input, and usage errors exit with code 1. Warnings alone do not
+make an otherwise valid receipt fail.
+
+To also verify a local artifact, supply a receipt containing `artifactChecksum`
+and the exact artifact file whose SHA-256 checksum was recorded in that receipt:
+
+```sh
+pnpm --filter @sub-rosa/receipt-cli receipt verify /absolute/path/to/receipt.json --json --verify-artifact-checksum /absolute/path/to/artifact.wasm
+```
+
+These are placeholder paths to your own files. A missing file, absent checksum
+metadata, or checksum mismatch fails verification. The golden-fixture commands
+above do not require an artifact file.
+
+## Export from RPC
+
+Export reads the configured network; it requires no transaction signing.
+Replace the contract ID and round ID with a deployed contract and existing round:
+
+```sh
+CONTRACT_ID='<deployed-round-contract-id>' pnpm --filter @sub-rosa/receipt-cli receipt export 1
+```
+
+The command writes `round-1-receipt.json` in the CLI workspace.
+
+| Variable | Meaning | Default |
+| --- | --- | --- |
+| `CONTRACT_ID` | Deployed round contract ID (`C…`) | Required |
+| `RPC_URL` | Soroban RPC endpoint | `https://soroban-testnet.stellar.org` |
+| `NETWORK_PASSPHRASE` | Network passphrase | `Test SDF Network ; September 2015` |
+
+## Redact a copy
+
+Use an explicit output path to keep the original receipt intact:
+
+```sh
+pnpm --filter @sub-rosa/receipt-cli receipt redact src/fixtures/golden.json /tmp/sub-rosa-receipt.redacted.json
+```
+
+For which fields are removed and how redaction affects verification, consult the
+[receipt guide](../../docs/RECEIPTS.md). Review the resulting file before publishing.
+
+## Development checks
+
+```sh
+pnpm receipt-cli:test
+pnpm receipt-cli:typecheck
+```