Weighted routing

Given for a dict of weights for OSM tags. This extends the binary PBI routing to a full-blown weighted routing framework.

For weight inspirations, look at people for bikes or osmr, for example, however, here the routing should prioritize the street infra that should be turned into pbi, so it's not the same, maybe even complementary.

No implementation file or test is named. Start by locating the existing binary PBI routing entry point and its tests, then review how OSM tags and street infrastructure are represented; done should be a defined weighted-routing framework whose priorities are agreed for streets to be converted into PBI.

Written by the indexing model from the issue text.