fix: register forum/thread routes at top level + notification dots in ServerBar

Moved thread and forum-tag routes from nested /servers/{sid}/channels/ to
top-level /channels/{id}/... to match frontend API calls. Forum posts were
getting SPA HTML fallback instead of JSON.

Added orange notification dots to DM and server buttons in ServerBar.

cmd/server/main.go

@@ -250,6 +250,19 @@ func main() {
 				r.Post("/", calHandler.CreateEvent)
 			})
 
+			// Threads (forum posts)
+			threadHandler := channel.NewHandler(database.DB, permissionsChecker)
+			r.Route("/channels/{channelID}/threads", func(r chi.Router) {
+				r.Get("/", threadHandler.ListThreads)
+				r.Post("/", threadHandler.CreateThread)
+			})
+			r.Patch("/threads/{threadID}", threadHandler.UpdateThread)
+
+			// Forum tags
+			r.Get("/channels/{channelID}/forum-tags", threadHandler.ListForumTags)
+			r.Post("/channels/{channelID}/forum-tags", threadHandler.CreateForumTag)
+			r.Delete("/forum-tags/{tagID}", threadHandler.DeleteForumTag)
+
 			// Push notifications
 			pushHandler.RegisterRoutes(r)