@W-23128917 document order hook lifecycle and two-hook pattern

[charithaT07]

@W-23157033 Add order hook rollback semantics, the afterPOST + modifyPOSTResponse two-hook pattern for persisting failed orders while returning HTTP errors, and request.custom inter-hook data passing to the b2c-hooks skill. Includes new ORDER-HOOK-LIFECYCLE.md reference and additional trigger eval queries.

Summary

• Document the SCAPI/OCAPI order hook lifecycle: beforePOST → afterPOST (inside txn) → modifyPOSTResponse (after commit)
• Document rollback semantics: Status.ERROR in afterPOST rolls back the order; in modifyPOSTResponse it does not
• Add the two-hook pattern for persisting a FAILED order AND returning HTTP 400 to the storefront
• Document request.custom as the idiomatic channel for inter-hook data passing
• Add ORDER-HOOK-LIFECYCLE.md reference with full code examples and verified sandbox results
• Add 2 new trigger eval queries covering the new content

Context

Follow-up to W-23128917. While building the production-triage demo on zzpq-019, we discovered that a single afterPOST hook cannot both persist a failed order and return an error — the b2c-hooks skill did not document this constraint or the
workaround.

Test plan

• Run pnpm run skills:eval -- --skill-path skills/b2c/skills/b2c-hooks to verify trigger accuracy
• Manual: ask Claude about order hook rollback behavior and confirm it references the new content

Dependencies

• No net-new third-party dependencies were added
• If net-new third-party dependencies were added, rationale/discussion is included and 3pl-approved is set by a maintainer

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• Tests pass (pnpm test)
• Code is formatted (pnpm run format)