Add an isClosedLoop toggle to route plans (schema v3 -> v4 migration),
threaded through the domain model, repository distance recomputation,
the overflow menu, and the drawn polyline, so a route can loop back to
its first waypoint.
Turns docs/FEEDBACK.md into five self-contained tickets, each grounded in
exact current code and a concrete implementation approach, so they can be
handed to independent subagents with no prior context.
