Accept policy_holder_id as an alias for id on policy-holder objects

[fuhrysteve]

What

resolvePolicyHolderId() accepts policy_holder_id as an alias for id on policy-holder objects, applied at the three boundaries where an id-less PH can enter the SDK:

• setStep4 normalizes integrator-passed policyHolder objects before storing them in state
• getPolicyHolder() backfills id on the single-PH GET response (the backend serializes policy_holder_id but not id on that endpoint), so the post-submit refresh paths keep a usable object in state
• PolicyHolderDetail degrades to a summary-less status card instead of fetching when no id resolves

StreamPolicyHolderShort gains an optional policy_holder_id field documenting the alias.

Why

A customer portal drives the wizard programmatically via the step callbacks (doneStep2 → choosePolicyHolder) and passes PH objects carrying policy_holder_id but no id. Verified in production traffic (nginx ES index, correlated with X-SDK-Version from SDKLogger):

• Starting exactly with their 0.8.2 upgrade (staging 2026-07-06, prod 2026-07-07), the new status view fetched .../policy_holder/undefined — a routing 404 on the CORS preflight, ~50/week across 18 member IPs. Silent to the member (the summary fetch is non-fatal) but the claim-sync summary never rendered.
• Worse and predating 0.8.2: with policyHolder.id undefined, a credential re-submit falls back from PUT (update-in-place) to POST (create). The backend POST upserts on (username, payer, user), so same-username fixes work — but a changed username creates a new PH and strands the original broken one as permanently "Invalid". That tenant shows 0 PUTs in 30 days (every other SDK customer PUTs routinely) and 842 duplicate member+payer PH groups.

The one-line fix on the integrator side is to include id, but any integrator round-tripping our own single-PH GET response hits the same trap, so the SDK should tolerate the alias.

Testing

• npm test (biome + tsc) green
• No behavior change for objects that already carry id: resolvePolicyHolderId prefers id and only falls back when it's null/undefined

[fuhrysteve]

Wrong repo - dev PRs go to LakeEriePartners/stream-connect-js-sdk; this repo takes release PRs only. Re-opened there.