fix(helm): configure app rollouts and document shared storage

[Jarvis636431]

Description

The Helm production example configures three App replicas with a shared ReadWriteOnce PVC, while the App update strategy is fixed to RollingUpdate.

• Add configurable App update strategies and rolling-update settings, preserving the existing defaults. Recreate omits the rollingUpdate block, and unsupported strategy types fail rendering.
• Update the production example to use one App replica with Recreate and explain the upgrade downtime.
• Add a multi-replica example using a pre-provisioned RWX claim and document its shared-storage requirements.
• Add seven template regression tests and run them in Helm CI.

Related Issue

Fixes #4106

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-12T06:48:33.024204Z	fc6dcd6	PR opened

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.