release: prepare 2026.09.01-r1

[soulteary]

Summary

• set the immutable image version and all release examples to 2026.09.01-r1
• document the WordPress 7.1 → bundled 7.1.0 local core update behavior and persistent-volume upgrade steps
• move the accumulated fixes into the 2026.09.01-r1 changelog entry
• correct 2026.08.31-r3 to its verified published status and preserve the pending-release gate until the new image is published

Verification

• git diff --check
• shell syntax check for every *.sh file
• bash tests/test-documentation.sh
• bash tests/test-release-availability.sh
• bash tests/test-entrypoint-reconcile.sh
• bash tests/test-cosign-signature-retry.sh
• bash tests/test-release-evidence.sh
• confirmed Git, Docker Hub, and GHCR do not currently expose 2026.09.01-r1
• CI run #62: validate, amd64 native, arm64 native, and arm/v7 fallback jobs all passed

[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 2026-09-01T15:44:28.079054Z	7b6e59c	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.