spec(brand-protocol): register verify_brand_claim and verify_brand_claims in static/schemas/source/index.json

[bokelley]

Follow-up flagged by the agent that implemented PR #4603 (#4542 bulk variant).

The gap

`static/schemas/source/index.json` is the schema registry that lists every protocol surface. PR #4540 added the `verify_brand_claim` task but didn't register it in `index.json`. PR #4603 added `verify_brand_claims` (bulk variant) and similarly didn't register — out of scope for the bulk PR.

Both tools work without the registry entry (consumers reach them via the task pages and direct schema fetches), but the registry is the canonical surface for tool discoverability via SDK codegen and capability tooling.

What to do

Add both tasks to `static/schemas/source/index.json` with the appropriate metadata (protocol family, status, schema refs). Match the existing pattern for brand-protocol tasks (`get_brand_identity`, `get_rights`, `acquire_rights`, `update_rights`).

Scope

• One-line registry additions per task
• Confirm via `npm run test:schemas` that the registry-consistency check passes after the addition

Trivial PR; can land standalone.

Related

• PR feat(brand-protocol): verify_brand_claim — federated authoritative verification #4540 — verify_brand_claim shipped
• PR feat(brand-protocol): verify_brand_claims — bulk variant (#4542) #4603 — verify_brand_claims bulk shipped