feat(s): reorder left sidebar & more UX improvements

[nilsnolde]

lots of things I did in the past hours (well, had done, thanks claude). mostly improve UX:

• re-order left sidebar: pull out (IMHO) most important costing options (for car, I guess..) and make everything a bit easier to grasp on first sight
• tile tab: removed showing layers of background maps, only valhalla & custom layers
• increase the "click radius" (whatever the hell you call that in UI lingo) around route geometries when hovering or choosing an alternate; that's been pretty cumbersome before
• increase the costing model icons size
• move the "cog" icon to "advanced settings" button beneath the "general settings"

[github-actions]

Preview is ready! 🚀 You can view it here: https://valhalla-app-tests.gis-ops.com/419