Unified feed view for the Favorites section

Currently, the "Favorites" section displays posts separated by their respective chats. While this is useful for staying organized within a specific context, it becomes cumbersome when a user wants to quickly scan updates from multiple favorite sources at once. To see what’s new across all favorites, I have to manually switch between different chat views, which breaks the flow of information consumption.

I propose adding a view-switching mechanism in the Favorites section. Users should be able to toggle between two display modes:

• Grouped View (Current): Posts are grouped by individual chats (as they are now).
• Unified Stream: A single continuous feed that aggregates posts from all favorited chats into one list, sorted chronologically (newest first).

This would allow users to treat their "Favorites" as a personalized high-priority timeline rather than just a collection of separate folders. The unified stream should ideally respect the chronological order (created_at descending) so that the most recent activity from any favorite source appears at the top. Optional: It would be great if users could select which specific favorite chats are included in this unified stream via checkboxes or a multi-select menu.