Add path coverage options and derive min/max zoom levels

[napakalas]

#191
This PR adds configurable path minimum and maximum coverage options and calculates minZoom and maxZoom values for path properties to improve zoom‑based rendering and interaction.

[dbrnz]

How do you see these options being set when remotely generating a map? Shouldn't they be settings in the map's manifest.json and under source control, as they will affect the appearance/behaviour of the resulting flatmap?

[napakalas]

Ah, yes — these options should be defined in the map’s manifest and kept under source control.
They control how path visibility behaves across zoom levels, so storing the configuration (e.g. enabling the feature and its coverage thresholds) ensures the generated map is reproducible and has consistent appearance and interaction.

[napakalas]

• enablePathZoomRange is introduced in the flatmap-source manifest as a boolean value.
• This attribute is used to determine whether to calculate a path’s minzoom and maxzoom values.

[dbrnz]

Hmm, I more expected there to be no --path-min-coverage etc options and that these values would be specified in the map's manifest.

The same can be said about the min/max zoom range -- they should be removed as a run-time option and defined in the manifest, the idea being that everything that determines the look and feel of a generated map is in its version controlled manifest.