Fix connector Connect: use the link flow and surface failures

Root cause found by probing the live API: Composio v3 rejects
POST /connected_accounts for Composio-managed OAuth auth configs with a
400 pointing at POST /connected_accounts/link, and the renderer threw
the failure away inside a .then, so clicking Connect did nothing and no
browser opened.

- createConnectedAccount now calls POST /connected_accounts/link with
  auth_config_id and user_id and reads connected_account_id and
  redirect_url; the local mirror records INITIALIZING until the poll
  adopts Composio's real status.
- Connect failures (and a blocked external-URL open) now show as a
  single line on the page instead of vanishing.

src/shared/commands/composio.ts

@@ -21,7 +21,6 @@ export interface ConnectComposioToolkitInput {
 
 export interface ConnectComposioToolkitResult {
   accountId: string;
-  status: string;
   redirectUrl: string | null;
 }