feat(#291): map layer toggles in the nav panel

Epic D. The Map view has no list, so its nav panel was empty. It now carries
the map's own layer controls.

Those six toggles (chat nodes, repeaters, other nodes, discovery contacts,
guessed locations, overlaps) previously existed only in a modal behind the
floating button, so filtering the map meant covering the map with a dialog to
do it. In the panel, and especially pinned on a wide screen, they stay visible
and the map updates underneath as they are flipped.

Both surfaces read and write the same AppSettings, so a change in one is
reflected in the other. The floating-button dialog is deliberately left in
place: on a phone it is fewer taps than opening the drawer, and the panel is
the pinned-desktop path. If that duplication is unwanted, removing the dialog
is a one-line follow-up.

No new settings or storage; the existing setters were reused unchanged.

flutter analyze clean, dart format clean, 469 tests pass. Not yet run on
hardware.

lib/screens/map_screen.dart

@@ -24,6 +24,7 @@ import '../services/map_tile_cache_service.dart';
 import '../utils/contact_search.dart';
 import '../utils/route_transitions.dart';
 import '../widgets/app_shell.dart';
+import '../widgets/map_layer_panel.dart';
 import '../widgets/sync_progress_overlay.dart';
 import '../icons/los_icon.dart';
 import 'channels_screen.dart';
@@ -418,6 +419,7 @@ class _MapScreenState extends State<MapScreen> {
                 _handleQuickSwitch(index, context),
             contactsUnreadCount: connector.getTotalContactsUnreadCount(),
             channelsUnreadCount: connector.getTotalChannelsUnreadCount(),
+            drawerContent: const MapLayerPanel(),
             onDisconnect: () => _disconnect(context, connector),
             onSettings: () => Navigator.push(
               context,

lib/widgets/map_layer_panel.dart

@@ -0,0 +1,99 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../l10n/l10n.dart';
+import '../services/app_settings_service.dart';
+
+/// Map layer toggles for the nav panel.
+///
+/// The Map view has no list to show, so its panel carries the layer controls
+/// that otherwise live in a modal behind the floating button. Pinned on a wide
+/// screen these stay visible and the map updates underneath as they are
+/// flipped, instead of a dialog covering the thing being filtered.
+///
+/// The same settings back both surfaces, so a change here shows in the dialog
+/// and vice versa.
+class MapLayerPanel extends StatelessWidget {
+  const MapLayerPanel({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final service = context.watch<AppSettingsService>();
+    final settings = service.settings;
+    final l10n = context.l10n;
+    final theme = Theme.of(context);
+
+    return ListView(
+      padding: EdgeInsets.zero,
+      children: [
+        _sectionHeader(theme, l10n.map_nodeTypes),
+        _toggle(
+          label: l10n.map_chatNodes,
+          icon: Icons.person_outline,
+          value: settings.mapShowChatNodes,
+          onChanged: service.setMapShowChatNodes,
+        ),
+        _toggle(
+          label: l10n.map_repeaters,
+          icon: Icons.cell_tower,
+          value: settings.mapShowRepeaters,
+          onChanged: service.setMapShowRepeaters,
+        ),
+        _toggle(
+          label: l10n.map_otherNodes,
+          icon: Icons.help_outline,
+          value: settings.mapShowOtherNodes,
+          onChanged: service.setMapShowOtherNodes,
+        ),
+        const Divider(height: 1),
+        _sectionHeader(theme, l10n.map_filterNodes),
+        _toggle(
+          label: l10n.map_showDiscoveryContacts,
+          icon: Icons.person_search,
+          value: settings.mapShowDiscoveryContacts,
+          onChanged: service.setMapShowDiscoveryContacts,
+        ),
+        _toggle(
+          label: l10n.map_showGuessedLocations,
+          icon: Icons.location_searching,
+          value: settings.mapShowGuessedLocations,
+          onChanged: service.setMapShowGuessedLocations,
+        ),
+        _toggle(
+          label: l10n.map_showOverlaps,
+          icon: Icons.layers,
+          value: settings.mapShowOverlaps,
+          onChanged: service.setMapShowOverlaps,
+        ),
+      ],
+    );
+  }
+
+  Widget _sectionHeader(ThemeData theme, String label) {
+    return Padding(
+      padding: const EdgeInsets.fromLTRB(16, 12, 16, 4),
+      child: Text(
+        label,
+        style: theme.textTheme.labelMedium?.copyWith(
+          color: theme.colorScheme.onSurfaceVariant,
+          fontWeight: FontWeight.w700,
+        ),
+      ),
+    );
+  }
+
+  Widget _toggle({
+    required String label,
+    required IconData icon,
+    required bool value,
+    required ValueChanged<bool> onChanged,
+  }) {
+    return SwitchListTile(
+      dense: true,
+      secondary: Icon(icon, size: 20),
+      title: Text(label, maxLines: 2, overflow: TextOverflow.ellipsis),
+      value: value,
+      onChanged: onChanged,
+    );
+  }
+}