fix(map): Normalize winding order to CCW & replace d3-geo with turf LINDASSUP-247

[hupf]

Closes LINDASSUP-247

• Previously the received winding order of polygons has not been modified. This caused issues with helpers relying on a specific winding order. We now "rewind" all polygons to CCW ("right hand rule"), right after parsing, as is the standard with GeoJSON.
• The d3-geo helpers rely on a CW winding order, which would require a rewinding before each call. Therefore d3-geo is now replaced with equivalent helpers from turf, that use the CCW winding order, or polylabel which is winding order agnostic.

How to test

• Create a map visualization for Heavy Metal Soil Contamination: The map should be zoomed to Switzerland, not the whole world (this was the current bug).
• Symbols on maps should render correctly → see "Verkehrsleistung auf den Flugplätzen"
• Overlapping smaller regions should be in front of larger regions such they can be hovered and display a tooltip → see "NFI: Topics by extent of damage gaps (10 classes)"
• Data points should be centered correctly to the areas → see "NFI: Topics by extent of damage gaps (10 classes)", then add "Symbols" and choose "Canton"

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• I added a CHANGELOG entry
• I made a self-review of my own code
• I wrote tests for the changes (if applicable)
• I wrote configurator and chart config migrations (if applicable)

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Project	Deployment	Actions	Updated (UTC)
visualization-tool	Ready	Preview, Comment	Apr 27, 2026 11:46am