Add Journey screen: next connections for a fixed daily commute

New screens/journey.py, ported and simplified from github.com/EiS94/db_info
(a Home Assistant integration). Deliberately uses only the regional EFA
(Elektronische Fahrplanauskunft) backends the reference project queries
(VRR prioritized for NRW routes, falling back to Bavaria/BW instances) and
drops its bahn.de-internal-API source entirely -- that's DB's own
infrastructure, exactly the kind of thing DB has been actively blocking
(see the Departures screen). EFA instances are run by regional transit
authorities, not DB, so they aren't part of that clampdown. Also dropped
the reference project's parallel async fetch-and-score-all-sources
machinery for simple sequential fallback, matching this project's fully
synchronous style.

Verified against live VRR data for a real NRW route (Münster -> Dortmund):
real trains, platforms, transfer counts, even a night bus connection.

Caught a real bug during that live test: EFA returns UTC timestamps (Z
suffix), and datetime.fromisoformat() parses that correctly into an
aware datetime, but strftime() on an aware datetime prints its own
stored hour/minute rather than converting to local time first --
everything displayed 2 hours behind (CEST is UTC+2), which looked like
"next" departures had already left. Fixed by converting with
astimezone() before formatting; re-verified live afterward that
departures now correctly show after the query time.

Settings: origin/destination resolved via Open-Meteo's free geocoding
(same pattern as Weather's city field), how many connections to show
(1/2/3/5), and its own configurable update interval.

screens/__init__.py

@@ -1,5 +1,6 @@
 from screens.clock import ClockScreen
 from screens.departures import DeparturesScreen
+from screens.journey import JourneyScreen
 from screens.navidrome import NavidromeScreen
 from screens.picture import PictureScreen
 from screens.weather import WeatherScreen
@@ -8,6 +9,7 @@ SCREEN_CLASSES = {
     ClockScreen.id: ClockScreen,
     WeatherScreen.id: WeatherScreen,
     DeparturesScreen.id: DeparturesScreen,
+    JourneyScreen.id: JourneyScreen,
     PictureScreen.id: PictureScreen,
     NavidromeScreen.id: NavidromeScreen,
 }