feat(circuit-chauffeur): collapsible chaining detail in driver selection UI
Show driver chaining detail on demand and map algo chaining fields in the chauffeur stepper.
UI:
- PlanDriverChainingDetail: Voir detail enchainement / Masquer with Collapse
- PerNewTripContextList: direct chaining rows, expandable et N autres, Enchainement direct label
- ExistingTripsSummaryList: same expand pattern
- DriverSelect, DriverPlanCard, MultiDriverPlanSection: shared component
- SelectedPlanDetailsCard: always expanded; avoid duplicate proposalReason
- Fix driver list on reassignment and align mobility field in usager form