[fix][R2-2346] Add terminationGracePeriodSeconds and preStop hook to agent-executor proxy

[emas-rt]

Summary

• Adds terminationGracePeriodSeconds: 30 to the agent-executor proxy pod spec
• Adds lifecycle.preStop sleep of 5s to the proxy container

Without terminationGracePeriodSeconds, kubelet's default 30s still applies but there's no preStop hook, so SIGTERM can arrive before kube-proxy finishes removing the endpoint — new connections still route to the terminating pod. The preStop sleep covers that gap, and terminationGracePeriodSeconds: 30 ensures kubelet doesn't SIGKILL during the drain window (proxy has a 10s DRAIN_TIMEOUT_MS).

Closes R2-2346.

Test Plan

• CI green
• helm template diff shows only the two new fields on the proxy deployment, not the controller

[greptile-apps]

Add proxy shutdown rendering coverage

The agent-sandbox fixtures do not assert that these shutdown fields render only on the proxy deployment. Add a focused Helm rendering test covering both terminationGracePeriodSeconds and the preStop hook so future template changes cannot silently remove or misplace them.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[greptile-apps]

Confidence Score: 4/5

The PR appears safe to merge, although the previously requested regression coverage remains absent.

The shutdown fields are correctly scoped to the proxy, but existing CI only schema-validates rendered manifests and does not protect their presence or proxy-only placement against future template regressions.

Files Needing Attention: charts/retool/templates/deployment_agent_sandbox.yaml

Important Files Changed

Filename	Overview
charts/retool/templates/deployment_agent_sandbox.yaml	Adds the proxy pod termination grace period and container preStop lifecycle hook at the intended deployment and container scopes.
charts/retool/Chart.yaml	Bumps the chart patch version to publish the template update.

_{Reviews (2): Last reviewed commit: "[chore] bump chart version to 6.11.13" | Re-trigger Greptile}