chore(client): bump chart 1.3.1 -> 1.3.2 (develop sync)

[saadqbal]

Summary

• Cherry-pick of #114 onto develop so the dev branch tracks the chart version published from main.
• Same single commit as the prod-side bump: client/Chart.yaml 1.3.1→1.3.2 and the matching MIGRATION.md cadence note.

The actual release tag (v1.3.2) is cut from main after #114 merges; this PR exists purely to keep develop's Chart.yaml from drifting backwards.

Refs #111.

Test plan

• helm lint --strict ./client -f client/ci/eks-values.yaml clean
• helm unittest client/ — 116/116 pass at 1.3.2

🤖 Generated with Claude Code

[LukasWodka]

👋 Heads-up — Code review queue is at 11 / 8

Above the WIP limit. The team convention is to review existing PRs before opening new work.

Open PRs currently in Code review (oldest first):

• client#114 — chore(client): bump chart 1.3.1 -> 1.3.2 (hourly auto-upgrade) · author: @saadqbal · no reviewer assigned
• docs#14 — docs: migrate join-use-case API examples to snake_case (0.7.0) · author: @divyasinghds · no reviewer assigned
• docs#26 — docs: add "How training works" page · author: @divyasinghds · no reviewer assigned
• docs#4 — docs: switch install to extras syntax for tracebloc_package 0.6.33 · author: @LukasWodka · reviewer: @saadqbal
• documentation-lagecy-#7 — docs: migrate start-training and hyperparameters to snake_case API (0.7.0) · author: @aptracebloc · reviewer: @LukasWodka
• start-training#10 — ci: add WIP-limit-check caller workflow · author: @LukasWodka · no reviewer assigned
• start-training#6 — chore: add PR template + customer bump + stale auto-close · author: @LukasWodka · no reviewer assigned
• start-training#9 — ci: add kanban closure-routing caller workflow · author: @LukasWodka · reviewer: @saadqbal
• tracebloc-py-package#117 — TEST: trigger WIP-limit-check (do not merge — will close shortly) · author: @saadqbal · no reviewer assigned
• tracebloc-website#276 — docs(homepage): fix Colab install snippet to use tracebloc_package with extras · author: @LukasWodka · reviewer: @saadqbal

Pull from review before opening new work. (This is a nudge from the kanban WIP check, not a block.)