calculator and login improvements

lib/components/calculator/calculator.dart

@@ -66,9 +66,26 @@ class _StationAutocompleteState extends State<StationAutocomplete> {
       fieldViewBuilder:
           (context, textEditingController, focusNode, onFieldSubmitted) {
             textEditingController.value = _controller.value;
+
             return TextField(
               controller: textEditingController,
               focusNode: focusNode,
+              textInputAction: TextInputAction.done,
+              onSubmitted: (_) {
+                final query = textEditingController.text.toLowerCase();
+                final matches = widget.allStations
+                    .map((s) => s.name)
+                    .where((name) => name.toLowerCase().contains(query))
+                    .toList();
+
+                if (matches.isNotEmpty) {
+                  matches.sort((a, b) => a.length.compareTo(b.length));
+                  final firstMatch = matches.first;
+                  _controller.text = firstMatch;
+                  widget.onChanged(firstMatch);
+                  focusNode.unfocus(); // optionally close keyboard
+                }
+              },
               decoration: const InputDecoration(
                 labelText: 'Select station',
                 border: OutlineInputBorder(),