Planner now tries a route over roads you have actually ridden before
falling back to BRouter public data:
- Rust get_ride_graph(min_speed): nodes snapped to ~20m grid (walk=1
points excluded), edges between consecutive same-session points with
weight = node-to-node distance (consecutive-point distance loses
intra-cell travel and makes Dijkstra underestimate).
- JS loadRideGraph cache, grid-indexed nearest-node, Dijkstra, rideRoute
(snap <=60m, drop if >2.5x straight line).
- routeDirty: rideRoute first, BRouter(+nogos) in the gaps. Ridden leg
has no elevation -> thin line; BRouter -> casing (visually distinct).
- formatDistance now rounds metres (was 966.145...m).