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