fix(mobile): split escaped voice-note links into their own segment

mobile/lib/features/channels/message_content/bubble_segments.dart

@@ -1,4 +1,5 @@
 import '../message_media.dart';
+import 'markdown_escapes.dart';
 
 /// Splits top-level media from text without breaking Markdown blocks.
 /// Fenced code, lists and quotes retain their nested content.
@@ -44,7 +45,9 @@ List<({String text, bool attachment})> messageBubbleSegments(
         : embed.firstMatch(line.trimRight());
     final isAttachment =
         match != null &&
-        (line.trim().startsWith('!') || imeta.containsKey(match.group(1)));
+        (line.trim().startsWith('!') ||
+            // Content arrives with escapes shielded; imeta keys are plain.
+            imeta.containsKey(unshieldMarkdownEscapes(match.group(1)!)));
     if (attachment != null &&
         isAttachment != attachment &&
         line.trim().isNotEmpty) {

mobile/lib/features/channels/message_gallery.dart

@@ -43,7 +43,8 @@ TrailingImageGallery? extractTrailingImageGallery(
   while (cursor >= 0) {
     final match = imagePattern.firstMatch(lines[cursor].trim());
     if (match == null) break;
-    final url = match.group(2)!;
+    // CommonMark unescapes link destinations, as it does labels below.
+    final url = unshieldMarkdownEscapes(shieldMarkdownEscapes(match.group(2)!));
     final imeta = imetaByUrl[url];
     final mediaKind = classifyMediaUrl(url, imeta: imeta);
     if (mediaKind != MessageMediaKind.image) {

mobile/test/features/channels/message_content_bubble_cases.dart

@@ -240,9 +240,10 @@ void bubbleContentTests() {
       _testable(
         const MessageContent(
           content:
-              'Before\n\n[file.txt](https://example.com/file.txt)\n\nAfter',
+              // The escaped destination must still match its plain imeta URL.
+              'Before\n\n[file.txt](https://example.com/file\\_a.txt)\n\nAfter',
           tags: [
-            ['imeta', 'url https://example.com/file.txt', 'm text/plain'],
+            ['imeta', 'url https://example.com/file_a.txt', 'm text/plain'],
           ],
           bubble: true,
         ),

mobile/test/features/channels/message_content_test.dart

@@ -1924,7 +1924,8 @@ void main() {
         'groups uploaded photos into a carousel and opens the full gallery',
         (tester) async {
           const first = 'https://example.com/media/one.png';
-          const second = 'https://example.com/media/two.png';
+          // The second destination is escaped; the carousel must unescape it.
+          const second = 'https://example.com/media/two_2.png';
           const third = 'https://example.com/media/three.png';
           await tester.pumpWidget(
             _testable(
@@ -1933,7 +1934,7 @@ void main() {
                     '''
 Photos
 ![image]($first)
-![image]($second)
+![image](https://example.com/media/two\\_2.png)
 ![image]($third)
 ''',
                 tags: [