style(transport_helper): fix capitalisation of Line.lineId

lib/transport_helper.dart

@@ -282,7 +282,7 @@ class Vehicle {
   Map<String, Object?> toMap() {
     return {
       "id": id,
-      "line": line.LineId,
+      "line": line.lineId,
     };
   }
 
@@ -313,7 +313,7 @@ class Vehicle {
 class Line {
   static const String tableName = "line";
 
-  String LineId;
+  String lineId;
   Station? destination;
   Station? direction;
   VehicleType mode;
@@ -322,7 +322,7 @@ class Line {
   Color? bgColor;
 
   Line({
-    required this.LineId,
+    required this.lineId,
     required this.name,
     required this.mode,
     this.fgColor,
@@ -331,7 +331,7 @@ class Line {
 
   Map<String, Object?> toMap() {
     return {
-      "lineid": LineId,
+      "lineid": lineId,
       "destination": destination,
       "direction": direction,
       "mode": mode,
@@ -350,7 +350,7 @@ class Line {
   ];
 
   factory Line.fromJson(Map<String, dynamic> json) => Line(
-    LineId: json["lineId"],
+    lineId: json["lineId"],
     name: json["name"],
     mode: _vehicleTypeAsCatCode[int.parse(json["catCode"])],
     fgColor: