Add delivery artifact linter

[Li-AmG]

Delivery

Related bounty: #92 / Frantic bounty #41

Artifacts delivered:

• scripts/delivery-artifact-linter.mjs
• docs/delivery-artifact-linter.md
• pass/fail fixtures under verify/fixtures/delivery-artifact-linter/

Verification

Commands that prove acceptance criteria:

runx --version
node scripts/delivery-artifact-linter.mjs --bounty-file verify/fixtures/delivery-artifact-linter/bounty-41.html --offline public_url=https://github.com/auscaster/frantic-board/pull/0 evidence_json=verify/fixtures/delivery-artifact-linter/evidence-valid.json receipt_ref=runx:receipt:sha256:fixture report=https://github.com/auscaster/frantic-board/blob/main/docs/delivery-artifact-linter.md pr_url=https://github.com/auscaster/frantic-board/pull/0
node scripts/delivery-artifact-linter.mjs --bounty-file verify/fixtures/delivery-artifact-linter/bounty-41.html --offline public_url=https://example.invalid/missing evidence_json=verify/fixtures/delivery-artifact-linter/evidence-invalid.json receipt_ref=not-a-receipt
node scripts/delivery-artifact-linter.mjs --bounty-url https://gofrantic.com/bounties/41 --offline public_url=https://github.com/auscaster/frantic-board/pull/0 evidence_json=verify/fixtures/delivery-artifact-linter/evidence-valid.json receipt_ref=runx:receipt:sha256:fixture report=https://github.com/auscaster/frantic-board/blob/main/docs/delivery-artifact-linter.md pr_url=https://github.com/auscaster/frantic-board/pull/0

Observed runx --version: runx-cli 0.6.8.

The invalid fixture catches four delivery mistakes: missing report, missing pr_url, invalid evidence_json, and malformed receipt_ref.

Receipt

Runx receipt link, if claimed: not claimed in GitHub PR; local validation used runx CLI 0.6.8.

Closes #92