chore(client): bump chart 1.3.0 -> 1.3.1 (auto-upgrade verification)

[saadqbal]

Summary

• Bumps chart 1.3.0 → 1.3.1.
• Used to exercise the third (and previously-unverified) code path of the Helm chart auto-update — deployed clients stay frozen on installed version #69 auto-upgrade CronJob — actual helm upgrade execution from inside the upgrader Pod against the live public repo.

The other two paths were already verified during the #69 release:

• current > latest: cluster on 1.3.0, public latest 1.2.3 → CronJob took the "deployed is ahead" branch and exited 0.
• current == latest: after v1.3.0 publish → CronJob took the "already at latest" branch.

This release closes the loop on the third branch.

Rolls up under #69 — no separate kanban ticket per CLAUDE.md.

Test plan

• Merge → tag v1.3.1 → release workflow publishes to gh-pages.
• Trigger the dev-cluster CronJob (tracebloc-templates) manually with kubectl create job --from=cronjob/tracebloc-auto-upgrade ….
• Confirm Pod logs upgrading 1.3.0 -> 1.3.1 then upgrade complete: 1.3.0 -> 1.3.1.
• Confirm helm history tracebloc -n tracebloc-templates shows a new revision and chart client-1.3.1.
• Confirm mysql-client and tracebloc-jobs-manager pods stayed running through the upgrade.

🤖 Generated with Claude Code

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Note

Low Risk
Low risk: only bumps Helm chart/app version metadata and adds documentation noting successful end-to-end validation of the existing auto-upgrade CronJob path.

Overview
Bumps the unified client Helm chart version/appVersion from 1.3.0 to 1.3.1.

Updates MIGRATION.md to record that the auto-upgrade CronJob successfully self-upgraded a live release from 1.3.0 → 1.3.1 without operator intervention.

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