fix: CLI client types mismatched server response format

- SessionResponse: use 'id' (int64) not 'session_id'/'client_id'
- StateResponse: match actual server response shape
- GetMembers: strip '#' from channel name for URL path
- These bugs prevented the CLI from working correctly with the server

cmd/chat-cli/api/client.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"strings"
 	"time"
 )
 
@@ -167,7 +168,9 @@ func (c *Client) ListChannels() ([]Channel, error) {
 
 // GetMembers returns members of a channel.
 func (c *Client) GetMembers(channel string) ([]string, error) {
-	data, err := c.do("GET", "/api/v1/channels/"+url.PathEscape(channel)+"/members", nil)
+	// Server route is /channels/{channel}/members where channel is without '#'
+	name := strings.TrimPrefix(channel, "#")
+	data, err := c.do("GET", "/api/v1/channels/"+url.PathEscape(name)+"/members", nil)
 	if err != nil {
 		return nil, err
 	}