Route-optimisation endpoint (see module docs). `/optimize` is an alias.

Optimised plan: summary, unassigned and routes[] with ordered steps[] (durations in seconds, distances in metres, locations echoed as {lat, lon}), plus the matrix profile used and, when any location sits in a UK clean-air zone or avoid_zones was set, a zones block naming those zones and the avoidance applied to the matrix. When territories was given, a territories block reports per-territory job counts (inside, assigned, unassigned), the jobs outside every territory, anything no vehicle was allowed to serve, and the semantics in force. When any vehicle declared reloads, each route carries its trip (1-based) beside the caller's own vehicle id, summary.routes counts TRIPS, and a reloads block reports trips used vs allowed, the depot, the trip windows and the sequencing approximation. When relax_if_unassigned was given, a relaxation block states whether a second solve ran, whether its plan is the one returned, what was widened and what is still unassigned