Per request: V3-08's routing-engine direction is decided (self-hosted OSRM over a hosted API or the public demo instance) but standing one up is split into its own ticket, V3-17, since provisioning a server is different work from the app code that calls it. V3-08 and V3-09 are marked Deferred pending V3-17.
V3-17 also names a real tension worth flagging rather than quietly ignoring: this backlog's own organizing principle is 'v3 is everything buildable with no server,' and a self-hosted OSRM instance is a server -- so V3-08/V3-09 sit oddly under docs/v3/ once V3-17 exists. Left unresolved by design (a documentation call for later), noted in both V3-17 and BACKLOG.md's v4 section rather than silently renumbering tickets that are already cross-referenced throughout the docs.