FEATURE: Mobile Chat Footer Redesign (#25161)

This update adds three tabs to the bottom of the chat overlay to make it easier for users to navigate chat on mobile.

As a result of this change:

- Direct Messages are now shown separately from public channels on mobile
- My Threads has now moved from the channel list to it's own tab on mobile
- My Threads can still be accessed on desktop via the sidebar and within the drawer channel list
- Chat back button has been updated to navigate to the correct tab (for both channels and threads)

Some special cases:

- If DMs are not used then the tab is not rendered
- If the user has no threads then the tab is not rendered
- If both the tabs for DMs and Threads aren't available then the whole footer will not be rendered
- Chat footer is only shown on the listing pages (DMs, Channels, My Threads)

---------

Co-authored-by: chapoi <101828855+chapoi@users.noreply.github.com>
Co-authored-by: Joffrey JAFFEUX <j.jaffeux@gmail.com>

plugins/chat/spec/system/navigation_spec.rb

@@ -38,11 +38,11 @@ RSpec.describe "Navigation", type: :system do
   end
 
   context "when clicking chat icon on mobile and is viewing channel" do
-    it "navigates to index", mobile: true do
+    it "navigates to direct messages tab", mobile: true do
       chat_page.visit_channel(category_channel_2)
       chat_page.open_from_header
 
-      expect(page).to have_current_path(chat_path)
+      expect(page).to have_current_path("/chat/direct-messages")
     end
   end