feat(#170): channel name-key resolution hides blocked senders

- Connector: resolveContactKeysByName(name) maps an anonymous channel sender
  (name-only) to matching contact/discovered pubkeys (self-heals via adverts
  keeping contact names current).
- channel_chat_screen: hide a post only when the name resolves and EVERY
  matching pubkey is blocked (ambiguous namesake with any unblocked match still
  shown), or the name is in blockedNames. View-layer filter only.

Epic A #165 / A3 #170. Design: docs/architecture/block-contract-as-built.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/connector/meshcore_connector.dart

@@ -695,6 +695,23 @@ class MeshCoreConnector extends ChangeNotifier {
     return _channelMessages[channel.index] ?? [];
   }
 
+  /// Public keys (hex) of known contacts / discovered nodes whose current
+  /// display name matches [name] (case-insensitive). Resolves an anonymous
+  /// channel sender (name-only, no pubkey) back to identities for block
+  /// matching. Multiple keys => several devices/people share the name.
+  List<String> resolveContactKeysByName(String name) {
+    final target = name.trim().toLowerCase();
+    if (target.isEmpty) return const [];
+    final keys = <String>{};
+    for (final c in contacts) {
+      if (c.name.trim().toLowerCase() == target) keys.add(c.publicKeyHex);
+    }
+    for (final c in discoveredContacts) {
+      if (c.name.trim().toLowerCase() == target) keys.add(c.publicKeyHex);
+    }
+    return keys.toList();
+  }
+
   Future<void> deleteChannelMessage(ChannelMessage message) async {
     final channelIndex = message.channelIndex;
     if (channelIndex == null) return;

lib/screens/channel_chat_screen.dart

@@ -24,6 +24,7 @@ import '../models/channel_message.dart';
 import '../models/translation_support.dart';
 import '../models/app_settings.dart';
 import '../services/app_settings_service.dart';
+import '../services/block_service.dart';
 import '../services/chat_text_scale_service.dart';
 import '../services/translation_service.dart';
 import '../utils/emoji_utils.dart';
@@ -348,8 +349,15 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
               child: Consumer<MeshCoreConnector>(
                 builder: (context, connector, child) {
                   final messages = connector.getChannelMessages(widget.channel);
-
-                  if (messages.isEmpty) {
+                  final blockService = context.watch<BlockService>();
+                  final visibleMessages = messages
+                      .where(
+                        (m) =>
+                            !_isChannelSenderHidden(m, connector, blockService),
+                      )
+                      .toList();
+
+                  if (visibleMessages.isEmpty) {
                     return Center(
                       child: Column(
                         mainAxisAlignment: MainAxisAlignment.center,
@@ -383,7 +391,7 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
                   }
 
                   // Reverse messages so newest appear at bottom with reverse: true
-                  final reversedMessages = messages.reversed.toList();
+                  final reversedMessages = visibleMessages.reversed.toList();
                   final itemCount =
                       reversedMessages.length + (_isLoadingOlder ? 1 : 0);
 
@@ -496,6 +504,21 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
     connector.setChannelUnreadCount(widget.channel.index, count);
   }
 
+  /// A channel post is hidden only when its claimed name resolves to at least
+  /// one identity and *every* matching pubkey is blocked (an ambiguous namesake
+  /// with any unblocked match is still shown), or the name is in blockedNames.
+  bool _isChannelSenderHidden(
+    ChannelMessage message,
+    MeshCoreConnector connector,
+    BlockService blockService,
+  ) {
+    if (message.isOutgoing) return false;
+    final name = message.senderName;
+    if (blockService.isNameBlocked(name)) return true;
+    final keys = connector.resolveContactKeysByName(name);
+    return keys.isNotEmpty && keys.every(blockService.isBlocked);
+  }
+
   Widget _buildMessageBubble(ChannelMessage message, double textScale) {
     final settingsService = context.watch<AppSettingsService>();
     final enableTracing = settingsService.settings.enableMessageTracing;