fix: Add a warning when deploying with the ADK Web UI enabled

The warning message shows that ADK Web is for development purposes only and should not be used in production, as it has access to all data. This warning is displayed when the `--with-ui` flag is used with `adk deploy` and `adk deploy to-gke`

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 839795361

src/google/adk/cli/cli_tools_click.py

@@ -110,6 +110,18 @@ class HelpfulCommand(click.Command):
 logger = logging.getLogger("google_adk." + __name__)
 
 
+_ADK_WEB_WARNING = (
+    "ADK Web is for development purposes. It has access to all data and"
+    " should not be used in production."
+)
+
+
+def _warn_if_with_ui(with_ui: bool) -> None:
+  """Warn when deploying with the developer UI enabled."""
+  if with_ui:
+    click.secho(f"WARNING: {_ADK_WEB_WARNING}", fg="yellow", err=True)
+
+
 @click.group(context_settings={"max_content_width": 240})
 @click.version_option(version.__version__)
 def main():
@@ -1429,6 +1441,8 @@ def cli_deploy_cloud_run(
         err=True,
     )
 
+  _warn_if_with_ui(with_ui)
+
   session_service_uri = session_service_uri or session_db_url
   artifact_service_uri = artifact_service_uri or artifact_storage_uri
 
@@ -1848,6 +1862,7 @@ def cli_deploy_gke(
       --cluster_name=[cluster_name] path/to/my_agent
   """
   try:
+    _warn_if_with_ui(with_ui)
     cli_deploy.to_gke(
         agent_folder=agent,
         project=project,