feat(train): search for places in the route planner, through Photon (ADR 0030, D50)

A `search` endpoint asks the instance's Photon (compose.search.yaml, Europe's
database from GraphHopper, renewed monthly) for people signed in, limited and
unlogged. The planner gets a field over its map: the places found nearest the
map's centre first, in the app's language; one chosen is the next waypoint.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/train/halkyon_train_flutter/lib/l10n/app_de.arb

@@ -397,6 +397,11 @@
   "routeProfileMtb": "Mountainbike",
   "routeTapHint": "Tipp auf die Karte, um einen Wegpunkt hinzuzufügen; halt einen gedrückt und zieh ihn, um ihn zu verschieben.",
   "routeUndo": "Letzten Wegpunkt entfernen",
+  "routeSearchHint": "Nach einem Ort suchen",
+  "routeSearchClear": "Suche leeren",
+  "routeSearchNothing": "Nichts gefunden.",
+  "routeSearchTooOften": "Gerade zu viele Suchen; versuch es in einer Minute noch einmal.",
+  "routeSearchUnreachable": "Die Suche ist gerade nicht erreichbar.",
   "routePlanning": "Wird geplant …",
   "routeRefusedInvalid": "Ein Wegpunkt zu viel, oder einer außerhalb der Karte.",
   "routeRefusedTooOften": "Zu oft geplant: versuch es in einer Minute wieder.",

apps/train/halkyon_train_flutter/lib/l10n/app_en.arb

@@ -503,6 +503,13 @@
   "routeProfileMtb": "Mountain bike",
   "routeTapHint": "Tap the map to add a waypoint; hold one and drag it to move it.",
   "routeUndo": "Take the last waypoint off",
+  "routeSearchHint": "Search for a place",
+  "@routeSearchHint": {"description": "The planner's search field over the map (D50)."},
+  "routeSearchClear": "Clear the search",
+  "routeSearchNothing": "Nothing found.",
+  "@routeSearchNothing": {"description": "Under the planner's search: the instance found no place."},
+  "routeSearchTooOften": "Too many searches for now; try again in a minute.",
+  "routeSearchUnreachable": "The search can't be reached now.",
   "routePlanning": "Planning…",
   "routeRefusedInvalid": "A waypoint too many, or one off the map.",
   "routeRefusedTooOften": "Planned too often: try again in a minute.",

apps/train/halkyon_train_flutter/lib/l10n/app_localizations.dart

@@ -2404,6 +2404,36 @@ abstract class AppLocalizations {
   /// **'Take the last waypoint off'**
   String get routeUndo;
 
+  /// The planner's search field over the map (D50).
+  ///
+  /// In en, this message translates to:
+  /// **'Search for a place'**
+  String get routeSearchHint;
+
+  /// No description provided for @routeSearchClear.
+  ///
+  /// In en, this message translates to:
+  /// **'Clear the search'**
+  String get routeSearchClear;
+
+  /// Under the planner's search: the instance found no place.
+  ///
+  /// In en, this message translates to:
+  /// **'Nothing found.'**
+  String get routeSearchNothing;
+
+  /// No description provided for @routeSearchTooOften.
+  ///
+  /// In en, this message translates to:
+  /// **'Too many searches for now; try again in a minute.'**
+  String get routeSearchTooOften;
+
+  /// No description provided for @routeSearchUnreachable.
+  ///
+  /// In en, this message translates to:
+  /// **'The search can\'t be reached now.'**
+  String get routeSearchUnreachable;
+
   /// No description provided for @routePlanning.
   ///
   /// In en, this message translates to:

apps/train/halkyon_train_flutter/lib/l10n/app_localizations_de.dart

@@ -1432,6 +1432,22 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get routeUndo => 'Letzten Wegpunkt entfernen';
 
+  @override
+  String get routeSearchHint => 'Nach einem Ort suchen';
+
+  @override
+  String get routeSearchClear => 'Suche leeren';
+
+  @override
+  String get routeSearchNothing => 'Nichts gefunden.';
+
+  @override
+  String get routeSearchTooOften =>
+      'Gerade zu viele Suchen; versuch es in einer Minute noch einmal.';
+
+  @override
+  String get routeSearchUnreachable => 'Die Suche ist gerade nicht erreichbar.';
+
   @override
   String get routePlanning => 'Wird geplant …';
 

apps/train/halkyon_train_flutter/lib/l10n/app_localizations_en.dart

@@ -1425,6 +1425,22 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get routeUndo => 'Take the last waypoint off';
 
+  @override
+  String get routeSearchHint => 'Search for a place';
+
+  @override
+  String get routeSearchClear => 'Clear the search';
+
+  @override
+  String get routeSearchNothing => 'Nothing found.';
+
+  @override
+  String get routeSearchTooOften =>
+      'Too many searches for now; try again in a minute.';
+
+  @override
+  String get routeSearchUnreachable => 'The search can\'t be reached now.';
+
   @override
   String get routePlanning => 'Planning…';