Handle duplicate stack names across endpoints in console command

When a stack name exists on multiple endpoints, error with a list showing
each match with its endpoint ID and name. Pass --endpoint ID to disambiguate.
Single matches continue to work without any extra flags.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/portainer_cli.rb

@@ -31,6 +31,7 @@ module PortainerCli
         portainer-cli create stack    --endpoint ID --name NAME --file FILE
         portainer-cli create container --endpoint ID --image IMAGE [--name NAME] [--port h:c] [--env K=V]
         portainer-cli console <stack> [container]                Open interactive shell (resolves endpoint automatically)
+          --endpoint ID                                          Disambiguate when stack name exists on multiple endpoints
           --shell SHELL                                          Shell to use (default: /bin/sh)
           --run CMD                                              Run command instead of a bare shell
         portainer-cli exec <endpoint-id> <container>            Open interactive shell (manual endpoint)