fix(cli): address PR review warnings

- Skip known cloud LANGSMITH_ENDPOINT values so SaaS users' tracing
  env var doesn't hijack the deploy host URL
- Fix --image-uri help text to accurately describe build+push+deploy
  flow instead of claiming no build step
- Validate existing deployment source before PATCHing with
  --image-uri to give a clear error on incompatible deployments
- Move /api-host path strip before localhost check in
  _smith_dashboard_base_url so local self-hosted status URLs work
- Fix test_constructor_strips_trailing_slash to use base_url property
  instead of removed httpx base_url
- Apply ruff formatting

libs/cli/tests/unit_tests/test_host_backend.py

@@ -25,7 +25,7 @@ def client(mock_transport):
 
 def test_constructor_strips_trailing_slash():
     c = HostBackendClient("https://api.example.com/", "key")
-    assert str(c._client.base_url) == "https://api.example.com"
+    assert c.base_url == "https://api.example.com"
 
 
 def test_constructor_empty_url_raises():