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.

README.md

@@ -1,10 +1,10 @@
 # Paperwall
 
 A standalone dashboard for one Waveshare `epd4in0e` (4", 6-color) e-ink panel:
-Navidrome now-playing, clock, weather, train departures, and pictures
-(upload or URL), switchable/controllable from a local web UI. Started as an InkyPi
-replacement, but doesn't depend on InkyPi at all -- own venv, own vendored
-copy of the Waveshare driver files.
+Navidrome now-playing, clock, weather, departure boards, a fixed-route
+journey planner, and pictures (upload or URL), switchable/controllable from
+a local web UI. Started as an InkyPi replacement, but doesn't depend on
+InkyPi at all -- own venv, own vendored copy of the Waveshare driver files.
 
 Confirmed by reading the vendor driver directly: this panel has no
 partial-refresh mode at all -- every update is a full flash. So the design