feat(geocoding): add multi-provider support for LocationIQ and Geoapify

- Add GeocodingProvider enum (nominatim, locationIQ, geoapify) with
  display names, descriptions, and rate limits per provider
- Refactor geocoding service to route requests based on active provider
  with per-provider URL builders, response parsers, and throttle intervals
- Add provider preference to SettingsService with ValueNotifier for
  reactive UI updates
- Add 'Map API Provider' section in Settings screen with live tile
  selector showing rate limits and API key validation warnings

Author: Fury3K

lib/src/core/di/injection.config.dart

@@ -0,0 +1,31 @@
+enum GeocodingProvider {
+  nominatim,
+  locationIQ,
+  geoapify;
+
+  String get displayName {
+    switch (this) {
+      case GeocodingProvider.nominatim:
+        return 'Nominatim (OpenStreetMap)';
+      case GeocodingProvider.locationIQ:
+        return 'LocationIQ';
+      case GeocodingProvider.geoapify:
+        return 'Geoapify';
+    }
+  }
+
+  String get description {
+    switch (this) {
+      case GeocodingProvider.nominatim:
+        return 'Free, no API key. Limit: 1 req/sec.';
+      case GeocodingProvider.locationIQ:
+        return 'Free tier: 5,000 req/day, 2 req/sec.';
+      case GeocodingProvider.geoapify:
+        return 'Free tier: 3,000 req/day, 5 req/sec.';
+    }
+  }
+
+  bool get requiresApiKey =>
+      this == GeocodingProvider.locationIQ ||
+      this == GeocodingProvider.geoapify;
+}

lib/src/models/geocoding_provider.dart

@@ -9,6 +9,7 @@ import '../../core/di/injection.dart';
 import '../../l10n/app_localizations.dart';
 import '../../models/discount_type.dart';
 import '../../models/fare_formula.dart';
+import '../../models/geocoding_provider.dart';
 import '../../models/transport_mode.dart';
 import '../../repositories/fare_repository.dart';
 import '../../services/offline/offline_map_service.dart';
@@ -51,6 +52,7 @@ class _SettingsScreenState extends State<SettingsScreen>
   Locale _currentLocale = const Locale('en');
   bool _isLoading = true;
 
+  GeocodingProvider _geocodingProvider = GeocodingProvider.nominatim;
   bool _offlineModeEnabled = false;
   bool _autoCacheEnabled = true;
   bool _autoCacheWifiOnly = true;
@@ -113,6 +115,7 @@ class _SettingsScreenState extends State<SettingsScreen>
     final trafficFactor = await _settingsService.getTrafficFactor();
     final themeMode = await _settingsService.getThemeMode();
     final discountType = await _settingsService.getUserDiscountType();
+    final geocodingProvider = await _settingsService.getGeocodingProvider();
     final hiddenModes = await _settingsService.getHiddenTransportModes();
     final hasSetModePrefs = await _settingsService
         .hasSetTransportModePreferences();
@@ -154,6 +157,7 @@ class _SettingsScreenState extends State<SettingsScreen>
         _themeMode = themeMode;
         _trafficFactor = trafficFactor;
         _discountType = discountType;
+        _geocodingProvider = geocodingProvider;
         _currentLocale = locale;
         _hiddenTransportModes = hiddenModes;
         _hasSetTransportModePreferences = hasSetModePrefs;
@@ -230,6 +234,28 @@ class _SettingsScreenState extends State<SettingsScreen>
                   ),
                   const SizedBox(height: 24),
 
+                  // Map API Provider Section
+                  _buildSectionHeader(
+                    context,
+                    icon: Icons.map_rounded,
+                    title: 'Map API Provider',
+                  ),
+                  const SizedBox(height: 8),
+                  _buildSettingsCard(
+                    context,
+                    children: [
+                      _buildGeocodingProviderTile(
+                          context, GeocodingProvider.nominatim),
+                      const Divider(height: 1, indent: 56),
+                      _buildGeocodingProviderTile(
+                          context, GeocodingProvider.locationIQ),
+                      const Divider(height: 1, indent: 56),
+                      _buildGeocodingProviderTile(
+                          context, GeocodingProvider.geoapify),
+                    ],
+                  ),
+                  const SizedBox(height: 24),
+
                   // Appearance Section
                   _buildSectionHeader(
                     context,
@@ -541,6 +567,59 @@ class _SettingsScreenState extends State<SettingsScreen>
     );
   }
 
+  Widget _buildGeocodingProviderTile(
+      BuildContext context, GeocodingProvider provider) {
+    final theme = Theme.of(context);
+    final colorScheme = theme.colorScheme;
+    final isSelected = _geocodingProvider == provider;
+    final needsKey = provider.requiresApiKey;
+    final keyMissing = (provider == GeocodingProvider.locationIQ &&
+            AppConstants.locationIQApiKey == 'YOUR_LOCATIONIQ_API_KEY') ||
+        (provider == GeocodingProvider.geoapify &&
+            AppConstants.geoapifyApiKey == 'YOUR_GEOAPIFY_API_KEY');
+
+    return ListTile(
+      leading: Icon(
+        Icons.language_rounded,
+        color: isSelected ? colorScheme.primary : colorScheme.onSurfaceVariant,
+      ),
+      title: Text(
+        provider.displayName,
+        style: theme.textTheme.bodyLarge?.copyWith(
+          fontWeight: isSelected ? FontWeight.w600 : FontWeight.normal,
+          color: isSelected ? colorScheme.primary : colorScheme.onSurface,
+        ),
+      ),
+      subtitle: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Text(
+            provider.description,
+            style: theme.textTheme.bodySmall
+                ?.copyWith(color: colorScheme.onSurfaceVariant),
+          ),
+          if (needsKey && keyMissing)
+            Text(
+              'API key required — add to AppConstants',
+              style: theme.textTheme.bodySmall?.copyWith(
+                color: colorScheme.error,
+                fontWeight: FontWeight.w500,
+              ),
+            ),
+        ],
+      ),
+      trailing: isSelected
+          ? Icon(Icons.check_circle_rounded, color: colorScheme.primary)
+          : null,
+      onTap: needsKey && keyMissing
+          ? null
+          : () async {
+              setState(() => _geocodingProvider = provider);
+              await _settingsService.setGeocodingProvider(provider);
+            },
+    );
+  }
+
   /// Builds a section header with icon and title.
   Widget _buildSectionHeader(
     BuildContext context, {