Enhance search result zoom level

[benoit74]

For now, we set the zoom level based on ADM level in geonames:

maps/scraper/src/maps2zim/processor.py

Lines 1235 to 1240 in 3304033

	adm_zoom_map = {
	"ADM1": 6,
	"ADM2": 8,
	"ADM3": 10,
	"ADM4": 12,
	}

While "not totally wrong", this could definitely be fine-tuned. Big question is "how"?

[sga-13]

here my thoughts have changed a bit. what i meant back then was that in search index, each coordinate comes with a zoom level (higher for relatively small places, big for relatively big places). and when i wrote the comment, i tested for a place (small) i know, and it was marked for 12x, and i still could not see it, so updated the index line to 14 where it was visible. but then i tried unknown places, and there it became obvious that low zoom helps when i do not know where the place is, and less zoomed in view, some other known place would become visible. still not sure what is the way to go, maybe asking different people to test.

as to how i changed, i just de/incremented all zoom values with a editor shortcut

[benoit74]

Optimal value should ideally be based on place size. Unfortunately it seems hard to find such a dataset of good place labels with coordinates and approximate "width/height" or anything which can lead to a high quality zoom level. And obviously we do not want low quality proxies (like population) which only leads to even lower quality / less reliable results.