This PR extends the use of channelTopicLabelSpan function to additional locations:

1. Inbox page topic items - Now show channel icon + name + topic
2. All channels page entries - Unified channel icon + name display
3. Subscription list entries - Consistent channel icon + name
4. Stream recipient headers - Combined channel + topic display
5. Message list app bar - Unified channel/topic display for both ChannelNarrow and TopicNarrow

All changes maintain existing functionality while providing consistent styling
and improved visual recognition with channel icons throughout the UI.