Comment reactions

Reactions are a fun, lightweight way for people to acknowledge someone's message in a conversation. In addition to reacting to posts, you can now react to individual comments in a conversation.

Improvements

• The file preview dialog will default the canvas background to a user's theme preference.

Fixes

• Improved the contrast of selection states in the sidebar navigation.
• Fixed dark mode colors on links in post and comment bylines.
• Fixed dark mode colors on reactions.