fix(community): support new c-prefix handle format

Update formatHandleForDisplay to handle both formats:
- New: c-gaming.coves.social → ![e-mail]
- Legacy: gaming.community.coves.social → ![e-mail]

Add null fallback in PostCard._buildCommunityHandle to prevent
crashes when handle format is unrecognized.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[e-mail]>

lib/utils/community_handle_utils.dart

···
 /// Utility functions for community handle formatting and resolution.
 ///
 /// Coves communities use atProto handles in the format:
-/// - DNS format: `gaming.community.coves.social`
+/// - DNS format (new): `c-gaming.coves.social`
+/// - DNS format (legacy): `gaming.community.coves.social`
 /// - Display format: `![e-mail]`
 class CommunityHandleUtils {
   /// Converts a DNS-style community handle to display format
   ///
-  /// Transforms `gaming.community.coves.social` → `![e-mail]`
-  /// by removing the `.community.` segment
+  /// Supports both formats:
+  /// - New: `c-gaming.coves.social` → `![e-mail]`
+  /// - Legacy: `gaming.community.coves.social` → `![e-mail]`
   ///
-  /// Returns null if the handle is null or doesn't contain `.community.`
+  /// Returns null if the handle is null or doesn't match expected formats
   static String? formatHandleForDisplay(String? handle) {
     if (handle == null || handle.isEmpty) {
       return null;
     }
 
-    // Expected format: name.community.instance.domain
-    // e.g., gaming.community.coves.social
     final parts = handle.split('.');
 
-    // Must have at least 4 parts: [name, community, instance, domain]
-    if (parts.length < 4 || parts[1] != 'community') {
-      return null;
+    // New format: c-name.instance.domain (e.g., c-gaming.coves.social)
+    if (parts.length >= 3 && parts[0].startsWith('c-')) {
+      final communityName = parts[0].substring(2); // Remove 'c-' prefix
+      final instanceDomain = parts.sublist(1).join('.');
+      return '!$communityName@$instanceDomain';
     }
 
-    // Extract community name (first part)
-    final communityName = parts[0];
-
-    // Extract instance domain (everything after .community.)
-    final instanceDomain = parts.sublist(2).join('.');
+    // Legacy format: name.community.instance.domain
+    // e.g., gaming.community.coves.social
+    if (parts.length >= 4 && parts[1] == 'community') {
+      final communityName = parts[0];
+      final instanceDomain = parts.sublist(2).join('.');
+      return '!$communityName@$instanceDomain';
+    }
 
-    // Format as !name@instance
-    return '!$communityName@$instanceDomain';
+    // Unknown format - return null
+    return null;
   }
 
   /// Converts a display-style community handle to DNS format

lib/widgets/post_card.dart

···
   /// Builds the community handle with styled parts (name + instance)
   Widget _buildCommunityHandle(CommunityRef community) {
     final displayHandle =
-        CommunityHandleUtils.formatHandleForDisplay(community.handle)!;
+        CommunityHandleUtils.formatHandleForDisplay(community.handle);
+
+    // Fallback to raw handle or name if formatting fails
+    if (displayHandle == null || !displayHandle.contains('@')) {
+      return Text(
+        community.handle ?? community.name,
+        style: const TextStyle(color: AppColors.communityName, fontSize: 14),
+      );
+    }
 
     // Split the handle into community name and instance
     // Format: ![e-mail]