Find a good way to test/check the map app with Cypress

Our test looks like this picture below, we need to find a good way to verify the map result, like, the data on the map was loaded correctly, say, there are several cluster icons on the map, it's not a normal/traditional case for testing, also, those cluster on the map isn't css+html, they are pictures.

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Some hints:

- Please read our [readme](https://github.com/Greenstand/treetracker-web-map-core#treetracker-web-map-core) for more information/guide/tutorial.
- Here is [an engineering book](https://greenstand.gitbook.io/engineering/) in Greenstand.
- To know more about our organization, visit our [website](https://greenstand.org).
- If you want to join the slack community (some resources need the community member's permission), please leave your email address.

Start with the repository README and the current Cypress test referenced in the issue, then review how map data and cluster icons appear in the map app. Define a repeatable verification for correctly loaded map data and visible clusters, including how image-based markers are checked. Done means the Cypress test reliably detects an incorrect or missing map result.

Written by the indexing model from the issue text.