[BUG] Tickets for combined NJ/IC trains will have NJ tickets shown as 0€

[Unicorn-Tulkas]

Describe the bug
When checking a combined IC/NJ train betterbahn will split the journey at the nearest station to the start and suggest using NJ for the rest of the travel. This is causd by NJ ticket prices being only available on demand through a different website so DB will not report any pricing. Betterbahn currently assumes 0€ for Nightjet tickets when they are more expensive than regular IC tickets.

To Reproduce
Steps to reproduce the behavior:

1. Choose a connection that uses combined IC/NJ trains. Like train pair IC60470/NJ470.
2. Paste to betterbahn
3. Betterbahn suggests booking a ticket using IC for the first stop and then switch to NJ (same train) showing big savings as it assumes the ticket price as 0€

Expected behavior
Betterbahn should either not suggest using Nightjet connections, since prices aren't available through DB, or show correct NJ prices.

Screenshots and Bahn share code

Verbindung am Do. 11.09.2025
• von Freiburg(Breisgau) Hbf, Abfahrt 22:58 Uhr Gl. 1 mit IC 60470
• nach Bremen Hbf, Ankunft 06:42 Uhr Gl. 8 mit IC 60470
Verbindung ansehen: https://www.bahn.de/buchung/start?vbid=4f226258-7561-4bb6-b63b-57ecef637231

Betterbahn version:

• current Docker image via Docker compose

[FunctionDJ]

#89 will fix "Shows 0€ as fallback if insufficient data". Unsure if that counts as fixing this issue fully.