chore: bump operator image to 0.1.50

[Mukil Loganathan (langchain-infra)]

Summary

• Bumps langgraph-operator image tag from 0.1.47 to 0.1.50 in the langsmith chart (values.yaml + README.md tag table).
• langgraph-dataplane chart still pins 0.1.36 and is intentionally untouched here — its operator version is tracked separately, see chore: bump operator in langgraph-dataplane #567.

Test plan

• helm lint charts/langsmith
• helm template charts/langsmith shows the operator image at 0.1.50
• Operator pod comes up cleanly with the new tag in a dev cluster

[Mukil Loganathan (langchain-infra)]

Folded into #692 — operator bump now lives on the readonly FIPS test branch so the CI exercises operator 0.1.50-fips.