feat(cli): update client to use unified command endpoint

- JoinChannel/PartChannel now send via POST /messages with command field
- ListChannels uses /channels instead of /channels/all
- gofmt whitespace fixes

cmd/chat-cli/api/client.go

@@ -148,21 +148,19 @@ func (c *Client) PollMessages(afterID string, timeout int) ([]Message, error) {
 	return msgs, nil
 }
 
-// JoinChannel joins a channel.
+// JoinChannel joins a channel via the unified command endpoint.
 func (c *Client) JoinChannel(channel string) error {
-	_, err := c.do("POST", "/api/v1/channels/join", map[string]string{"channel": channel})
-	return err
+	return c.SendMessage(&Message{Command: "JOIN", To: channel})
 }
 
-// PartChannel leaves a channel.
+// PartChannel leaves a channel via the unified command endpoint.
 func (c *Client) PartChannel(channel string) error {
-	_, err := c.do("DELETE", "/api/v1/channels/"+url.PathEscape(channel), nil)
-	return err
+	return c.SendMessage(&Message{Command: "PART", To: channel})
 }
 
 // ListChannels returns all channels on the server.
 func (c *Client) ListChannels() ([]Channel, error) {
-	data, err := c.do("GET", "/api/v1/channels/all", nil)
+	data, err := c.do("GET", "/api/v1/channels", nil)
 	if err != nil {
 		return nil, err
 	}