fix: TYPING_START events now carry user_id and username

The backend was broadcasting TYPING_START with only channel_id.
Frontend required user_id + username to show who is typing.
Added Username to Client struct, fetched on WS connect via JOIN.
Typing events now enriched with sender identity before broadcast.

internal/gateway/client.go

@@ -105,6 +105,7 @@ type Client struct {
 	Hub      *Hub
 	Conn     *websocket.Conn
 	UserID   string
+	Username string
 	send     chan []byte
 }
 
@@ -140,7 +141,19 @@ func (c *Client) readPump() {
 		c.Hub.RecordActivity(c.UserID)
 
 		switch event.Type {
-		case EventTypingStart, EventPresenceUpdate:
+		case EventTypingStart:
+			// Enrich with sender info so receivers know who is typing
+			var data map[string]interface{}
+			if raw, ok := event.Data.(json.RawMessage); ok {
+				json.Unmarshal(raw, &data)
+			}
+			if data == nil {
+				data = make(map[string]interface{})
+			}
+			data["user_id"] = c.UserID
+			data["username"] = c.Username
+			c.Hub.BroadcastEvent(Event{Type: event.Type, Data: data})
+		case EventPresenceUpdate:
 			c.Hub.BroadcastEvent(event)
 		case EventVoiceWhisper:
 			// Forward voice whispers only to the target user, not broadcast
@@ -247,11 +260,11 @@ func ServeWS(db *sql.DB, hub *Hub, logger *slog.Logger, w http.ResponseWriter, r
 		token = auth.Token
 	}
 
-	var userID string
+	var userID, username string
 	err = db.QueryRowContext(context.Background(),
-		`SELECT user_id FROM sessions WHERE token = $1 AND expires_at > NOW()`,
+		`SELECT u.id, u.username FROM sessions s JOIN users u ON u.id = s.user_id WHERE s.token = $1 AND s.expires_at > NOW()`,
 		token,
-	).Scan(&userID)
+	).Scan(&userID, &username)
 	if err != nil {
 		logger.Warn("ws auth: invalid session", "error", err)
 		conn.WriteMessage(websocket.TextMessage, []byte(`{"error":"invalid session"}`))
@@ -266,6 +279,7 @@ func ServeWS(db *sql.DB, hub *Hub, logger *slog.Logger, w http.ResponseWriter, r
 		Hub:      hub,
 		Conn:     conn,
 		UserID:   userID,
+		Username: username,
 		send:     make(chan []byte, 256),
 	}