fix: give chatbot pickups per-leg surcharges including the return leg

docs/api-consumer-guide.md

@@ -318,6 +318,8 @@ returns it in one page.
           "city": "Frankfurt",
           "street": "Flughafen (P36 zwischen Terminal 1 und 2)",
           "price": 5.9,
+          "returnLeg": true,
+          "returnPrice": 5.9,
           "datetime": "2026-12-03T23:30:00"
         }
       ],
@@ -389,7 +391,9 @@ such as for arriving by car.
 `GET /api/exports/travels` — a clock reading without an offset, `null` where upstream states no time — including
 rolling a bare time past midnight onto the next day. There is no separate `time` field; format `datetime` for
 display. `price` is the outbound boarding surcharge exactly as upstream states it: `null` where upstream states
-none. It is not levelled against the return leg. An id absent from
+none. The surcharge is charged **per leg**: `returnLeg` says whether the point is also served on the way back, and
+`returnPrice` is its return surcharge, again verbatim and `null` where upstream states none. Neither price is levelled
+against the other. A point served on the return leg only is not emitted. An id absent from
 `GET /api/pickups` is emitted with `code`, `city` and `street` null and counted in `pickupsWithoutMasterData`. An id
 of `0` is emitted as-is but not counted.