Fix duplicate HTML when map.save() is called repeatedly

[vraj2131]

Summary

• Use stable script names for SetIcon and ElementAddToElement so repeated save() calls replace JavaScript instead of appending duplicates
• Avoid clearing figure.html during render() so geopandas legend HTML added directly to the figure is preserved
• Add regression test ensuring multiple save() calls produce identical HTML

Fixes #2237

Test plan

• pytest tests/test_map.py::test_repeated_save_produces_identical_html
• pytest geopandas/tests/test_explore.py legend tests (categorical legend, colorbar, mapclassify)
• pytest tests --ignore=tests/selenium
• pre-commit run on changed files

[banderlog]

neuroslope

[hansthen]

Seems like a sensible change. I do not understand everything yet. Why is the render method redefined?

[banderlog]

Changes are irrelevant

[banderlog]

Changes are irrelevant

[banderlog]

Changes are irrelevant

[banderlog]

Adding elements.ElementAddToElement.render() AND map.Marker.SetIcon.render() actually solves the problem -- output HTML files will have identical md5hash.

But I have no idea why

UPD: all other changes, except those two above mentioned functions are irrelevant

[banderlog]

Changes are irrelevant

[vraj2131]

The default path uses a new random script name each render, the overrides use deterministic names tied to the element or marker, so repeated save() updates the same script slot instead of duplicating it.

[hansthen]

Running the automated tests now.

[vraj2131]

Publish Docs fails on an external WMS timeout in WmsTimeDimension.md, issue is not from this PR?

[hansthen]

Publish Docs fails on an external WMS timeout in WmsTimeDimension.md, issue is not from this PR?

Correct. Will merge.