Revert "Build post chat and attachment workflows"

This reverts commit 0b920da187.

backend/internal/calendar/chat_events.go

@@ -1,55 +0,0 @@
-package calendar
-
-import "sync"
-
-type ChatEventHub struct {
-	mu          sync.Mutex
-	subscribers map[string]map[chan struct{}]struct{}
-}
-
-func NewChatEventHub() *ChatEventHub {
-	return &ChatEventHub{
-		subscribers: map[string]map[chan struct{}]struct{}{},
-	}
-}
-
-func (h *ChatEventHub) Subscribe(itemID string, channel string) (chan struct{}, func()) {
-	key := chatEventKey(itemID, channel)
-	events := make(chan struct{}, 1)
-
-	h.mu.Lock()
-	if h.subscribers[key] == nil {
-		h.subscribers[key] = map[chan struct{}]struct{}{}
-	}
-	h.subscribers[key][events] = struct{}{}
-	h.mu.Unlock()
-
-	return events, func() {
-		h.mu.Lock()
-		defer h.mu.Unlock()
-
-		delete(h.subscribers[key], events)
-		if len(h.subscribers[key]) == 0 {
-			delete(h.subscribers, key)
-		}
-		close(events)
-	}
-}
-
-func (h *ChatEventHub) Publish(itemID string, channel string) {
-	key := chatEventKey(itemID, channel)
-
-	h.mu.Lock()
-	defer h.mu.Unlock()
-
-	for events := range h.subscribers[key] {
-		select {
-		case events <- struct{}{}:
-		default:
-		}
-	}
-}
-
-func chatEventKey(itemID string, channel string) string {
-	return itemID + ":" + channel
-}