JSON data adapter: support target-named keys (not just 'entities')

[semanticintent]

Enhancement

The JSON data adapter's ensureLoaded() currently expects either:

• A bare array [...]
• An object with an "entities" key: {"entities": [...]}

When using FORAGE tech_companies, the natural data shape would be:

{"tech_companies": [...]}

But this returns 0 results because data.entities is undefined.

Proposed fix: In ensureLoaded(target), check for data[target] before falling back to data.entities:

const entities = Array.isArray(data) ? data : data[target] || data.entities || [];

Found during: cal-tutorials EP01 setup.