Clarify Departures covers bus/tram/subway too, add clear found/not-found feedback

The API (HAFAS via db-vendo-client) covers all public transport in one
system, not just trains -- verified with a mocked bus-stop response
(Bus 14/Bus 9/Bus 66 mixed with a regional train, all rendering correctly,
no code changes needed since nothing in check()/render() ever filtered by
mode). Fixed the "Train departures" wording in code comments and settings
UI, which was misleadingly train-specific.

Also added an explicit "Found: <station>" confirmation toast on a
successful station lookup, distinct from the generic "Saved." toast --
previously the only feedback was a passive "Currently: X" hint, easy to
miss and not obviously tied to the save you just did.

web/app.py

@@ -123,7 +123,7 @@ def create_app(config, screens: dict, scheduler) -> Flask:
                         "results": results,
                         "update_minutes": update_minutes,
                     })
-                    return redirect(url_for("settings_departures", saved=1))
+                    return redirect(url_for("settings_departures", found=found["name"]))
             else:
                 config.update_screen_settings("departures", {"results": results, "update_minutes": update_minutes})
                 return redirect(url_for("settings_departures", saved=1))