feat(dayplan): choose the travel mode per segment (#1281) (#1651)

* feat(dayplan): persist per-leg and per-day travel mode (#1281)

The day-plan route used one transport mode for the whole day, held only in
ephemeral state. Store it instead: leg_transport_mode on an assignment is
the mode of the leg leaving that stop (null = inherit the day default), and
days gains a default_transport_mode. Both nullable, so existing itineraries
are unchanged.

Adds PUT /assignments/:id/transport and PUT /days/:id/transport — their own
endpoints so setting the day default can't wipe notes/title the way the
general day update would — mirroring the assignment_time path.

* feat(dayplan): choose the travel mode per segment (#1281)

Each leg between two stops now routes with its own mode, so a day can mix
walking, driving and plugin-routed legs. Tap the connector between two
places to change that leg's mode (desktop popup / mobile sheet); the
whole-day Foot/Car picker sets the persisted day default and leaves
explicitly-set legs alone. The connector and map redraw in the chosen mode,
and each route segment is tagged with the mode it was drawn in.

New strings across all 23 locales.

shared/src/assignment/assignment.schema.ts

@@ -39,6 +39,9 @@ export const assignmentSchema = z.object({
   notes: z.string().nullable().optional(),
   assignment_time: z.string().nullable().optional(),
   assignment_end_time: z.string().nullable().optional(),
+  // Per-segment travel mode (#1281): the transport mode of the leg LEAVING this
+  // stop for the next one. null = inherit the day's default_transport_mode.
+  leg_transport_mode: z.string().nullable().optional(),
   participants: z.array(assignmentParticipantSchema).optional(),
   created_at: z.string().optional(),
   place: assignmentPlaceSchema,
@@ -68,6 +71,12 @@ export const assignmentTimeRequestSchema = z.object({
 });
 export type AssignmentTimeRequest = z.infer<typeof assignmentTimeRequestSchema>;
 
+/** Set the leg's travel mode (a RouteProfileKey, or null to inherit the day default). */
+export const assignmentTransportRequestSchema = z.object({
+  transport_mode: z.string().nullable(),
+});
+export type AssignmentTransportRequest = z.infer<typeof assignmentTransportRequestSchema>;
+
 export const assignmentParticipantsRequestSchema = z.object({
   user_ids: z.array(z.number()),
 });