update asset tree to be interactive

[Ahmad-Wahid]

Description

This PR migrates the asset tree macro from Vega to ECharts and refreshes the visual design. It introduces interactive navigation (roam/pan), improved tooltip and click behavior, and updated node styling (icons, labels, highlight states) to provide a clearer and more engaging tree experience.

Look & Feel

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• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on code under GPL or other license that is incompatible with FlexMeasures

[read-the-docs-community]

Documentation build overview

📚 flexmeasures | 🛠️ Build #31803170 | 📁 Comparing ea7afcb against latest (c6bb60f)

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File	Status
api/v3_0.html	📝 modified

[nhoening]

It looks nicer indeed.
But can you explain how it is more interactive?

[nhoening]

Ah wait, the PR description says how.

[nhoening]

It's rather cool.
However, here is an example where for me the new look is overlapping too much, so I cannot see the real structure:

Also, the type icon is very dominant now, which is a pity if the type is not well supported.

[Ahmad-Wahid]

The current status look like this:

The icons and the text remain inside the asset objects.

The only issue with the design is that when we zoom out the area shrinks and we can see the tree only in that area.

here is the example:

[nhoening]

let me know when I should/can test