Improve `useItem` API to accept collection and item IDs instead of full URL

Start by reading the existing useItem and useCollection hooks, then inspect StacApiProvider and useStacApiContext to understand how the base URL is exposed. Define the new collection and item ID signature, update the hook's callers, documentation, examples, and migration guidance, and verify that the query uses the constructed collection-item path.

The current useItem hook requires users to pass the full URL of an item, which is redundant and inconsistent with other hooks in the library:

// Current API
const { item } = useItem('https://stac-catalog.com/collections/sentinel-2/items/abc123');

This design has several issues:

1. Redundancy: The StacApiProvider already knows the base API URL, yet users must construct the full URL themselves
2. Error-prone: Manual URL construction can lead to mistakes (typos, wrong separators, encoding issues)
3. Not portable: Hardcoded URLs make switching between environments (dev/staging/prod) difficult
4. Inconsistent API: useCollection takes just a collectionId, but useItem requires a full URL

Proposed Solution

Refactor useItem to accept collectionId and itemId parameters, then construct the URL internally using the stacApi from context:

// Proposed API
const { item } = useItem('sentinel-2', 'abc123');

// Or with an object for clarity:
const { item } = useItem({ collectionId: 'sentinel-2', itemId: 'abc123' });

This follows the STAC API spec pattern: /collections/{collectionId}/items/{itemId}

Benefits

1. Consistency: Matches the pattern used by useCollection
2. Simplicity: No manual URL construction required
3. Portability: Environment-agnostic (base URL comes from context)
4. Type safety: Parameters are clearly defined
5. Less error-prone: Reduces chance of URL construction mistakes

Implementation Details

The hook would:

1. Accept collectionId and itemId as parameters
2. Get stacApi from useStacApiContext()
3. Construct the URL using stacApi.baseUrl + /collections/${collectionId}/items/${itemId}
4. Use this constructed URL for the query

Breaking Change

⚠️ This is a breaking change that would require a major version bump.

The hook could detect which signature is being used based on the number/type of arguments.

Related

• Consider whether other hooks might benefit from similar improvements
• Update documentation and examples
• Add migration guide if this is a breaking change