docs(creative): clarify brand and catalog sourcing

[bokelley]

Summary

• define brand.json as the canonical source of master brand identity, with supported brand_kit_override fields taking per-call precedence
• preserve catalog item asset groups as product/item identity, including property- or franchise-level logos
• update the hotel catalog example so its logo is unambiguously property-level rather than a master brand mark
• add a patch changeset for the documentation clarification

Closes #5765.

Expert review

• documentation review: no findings
• protocol review: identified an ambiguous pre-existing “advertiser's logo” example; corrected it to a property-level logo and path before publication

Validation

• npm run test:schemas — 29 schema checks + 4 metadata checks passed across 693 schemas
• npm run test:json-schema — 268 schema-backed documentation examples passed
• npm run lint:schema-links
• npm run test:docs-nav — 21/21 passed
• commit gate: 1,042/1,042 general unit tests, 5,958 server tests passed with 30 skipped, and TypeScript typecheck passed
• push gate: changeset policy, version synchronization, schema-link convention, and docs navigation passed

[aao-secretariat]

Ladon verdict: Escalate to human review

Escalate — gated schema paths require human/CODEOWNERS approval.

This PR modifies static/schemas/source/core/brand-ref.json and static/schemas/source/core/creative-manifest.json, which fall under the deterministic hard approval gate (gated_paths: true). The current review_decision is REVIEW_REQUIRED, not APPROVED, so the gate is not satisfied and auto-approval is not permitted (decision rule row 2).

The change itself is a description-only clarification: a correct patch changeset plus expanded schema descriptions and a mirrored docs note in docs/creative/catalogs.mdx, establishing brand.json as the master brand-identity source. The reviewer found the schema descriptions, docs, and existing brand_kit_override merge semantics mutually coherent — no wire-shape change, no oneOf change, no dist edits, correct changeset type. No blocking findings were raised.

Escalation reasons:

• Touches gated path static/schemas/source/core/brand-ref.json (modified) — human/CODEOWNERS review required; review_decision is REVIEW_REQUIRED.
• Touches gated path static/schemas/source/core/creative-manifest.json (modified) — human/CODEOWNERS review required.

Once a real approval lands (review_decision: APPROVED), this clean diff can fall through to a normal approve.

Why human review

• Modifies gated path static/schemas/source/core/brand-ref.json; review_decision is REVIEW_REQUIRED, not APPROVED — human/CODEOWNERS review required.
• Modifies gated path static/schemas/source/core/creative-manifest.json; review_decision is REVIEW_REQUIRED, not APPROVED — human/CODEOWNERS review required.
• This PR touches a path under a hard, non-overridable approval gate (static/schemas/source/core/brand-ref.json (modified) matches static/schemas/source/**; static/schemas/source/core/creative-manifest.json (modified) matches static/schemas/source/**) and the current GitHub review decision is 'REVIEW_REQUIRED', not APPROVED. This is a hard gate enforced in code — Ladon cannot auto-approve until a human/CODEOWNERS approval is recorded, regardless of how clean the diff is.