data: Deutschland-Ticket filter for connection candidates

DeutschlandTicket.covers() maps ticket validity onto the existing
TrainClass boundary: everything except long-distance (ICE/IC/EC, night
trains, FlixTrain, WESTbahn - WB newly classified) is covered. The
connection planner drops uncovered candidates when the new switch is
on; it defaults to on when the feeder itself is a regional train, and
warns when the feeder itself is not covered.

Verified on the emulator: Augsburg -> Muenchen -> Nuernberg with the
filter lists only RE/RB candidates and rides the +62-late RE1 (100%
catch) instead of the ICEs, arrival 20:54 vs 20:04 unrestricted.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Uuc17uFNtbiYVko4QxwAvE