Show brand page related equipment

[Codex]

Brand pages lacked related equipment context, making it hard to see items for a brand. This change fetches brand-scoped equipment and renders it alongside brand details.

• API: Added optional brandId query filter to /api/equipment/items to return only equipment for the brand.
• UI: Brand detail page now fetches related equipment and displays it with existing table/cards, with error and empty states.

Example (brand filter on API):

const { data } = await useFetch('/api/equipment/items', {
  query: { brandId },
  transform: ({ data }) => data.map((item) => ({
    id: item.id.toString(),
    name: item.name,
    weight: item.weight
  }))
})

Model used: GPT-5 (Codex)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Show related items on brand page</issue_title>
<issue_description></issue_description>

Comments on the Issue (you are @codex[agent] in this section)

• Fixes Show related items on brand page #261

[github-actions]

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