fix: CLI poll loop used UUID instead of queue cursor (last_id)

The poll loop was storing msg.ID (UUID string) as afterID, but the server
expects the integer queue cursor from last_id. This caused the CLI to
re-fetch ALL messages on every poll cycle.

- Change PollMessages to accept int64 afterID and return PollResult with LastID
- Track lastQID (queue cursor) instead of lastMsgID (UUID)
- Parse the wrapped MessagesResponse properly

cmd/chat-cli/main.go

@@ -19,7 +19,7 @@ type App struct {
 	nick      string
 	target    string // current target (#channel or nick for DM)
 	connected bool
-	lastMsgID string
+	lastQID   int64 // queue cursor for polling
 	stopPoll  chan struct{}
 }
 
@@ -142,7 +142,7 @@ func (a *App) cmdConnect(serverURL string) {
 	a.client = client
 	a.nick = resp.Nick
 	a.connected = true
-	a.lastMsgID = ""
+	a.lastQID = 0
 	a.mu.Unlock()
 
 	a.ui.AddStatus(fmt.Sprintf("[green]Connected! Nick: %s, Session: %s", resp.Nick, resp.SessionID))
@@ -462,27 +462,28 @@ func (a *App) pollLoop() {
 
 		a.mu.Lock()
 		client := a.client
-		lastID := a.lastMsgID
+		lastQID := a.lastQID
 		a.mu.Unlock()
 
 		if client == nil {
 			return
 		}
 
-		msgs, err := client.PollMessages(lastID, 15)
+		result, err := client.PollMessages(lastQID, 15)
 		if err != nil {
 			// Transient error — retry after delay.
 			time.Sleep(2 * time.Second)
 			continue
 		}
 
-		for _, msg := range msgs {
+		if result.LastID > 0 {
+			a.mu.Lock()
+			a.lastQID = result.LastID
+			a.mu.Unlock()
+		}
+
+		for _, msg := range result.Messages {
 			a.handleServerMessage(&msg)
-			if msg.ID != "" {
-				a.mu.Lock()
-				a.lastMsgID = msg.ID
-				a.mu.Unlock()
-			}
 		}
 	}
 }