fix: 4 audit findings in professionals location flow

- Clear button (✕) now resets _cityMismatch and _detectedCity so banner and CTA unblock
- _citiesMatch: replace bidirectional contains with equality + word-prefix check to prevent 'Cali' matching 'Calima'
- ProfessionalsProvider: track _currentUserId to reset state on user change (cross-user leak)
- ProfessionalsProvider: store _lastSearch so setLocationContext preserves active search term

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/ui/views/dashboard_view.dart

@@ -178,7 +178,8 @@ class _DashboardViewState extends State<DashboardView> {
         .replaceAll(RegExp(r'[úù]'), 'u');
     final na = normalize(a);
     final nb = normalize(b);
-    return na.contains(nb) || nb.contains(na);
+    // Exact match, or one is a full-word prefix of the other (handles "Bogotá D.C." vs "Bogotá")
+    return na == nb || na.startsWith('$nb ') || nb.startsWith('$na ');
   }
 
   Future<void> _geocodeAndMoveMap(String address) async {
@@ -440,6 +441,8 @@ class _DashboardViewState extends State<DashboardView> {
                                 setState(() {
                                   _suggestions = [];
                                   _currentAddress = '';
+                                  _detectedCity = '';
+                                  _cityMismatch = false;
                                 });
                               },
                             )