[CI] Auto-update versions in localized content files

[vitorvasc]

• I have read and followed the Contributing docs, especially the "First-time contributing?" section.
• This PR has content that I did not fully write myself.
  • I used AI and I have read and followed the Generative AI Contribution Policy.
• I have the experience and knowledge necessary to understand, review, and validate all content in this PR.¹

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The version auto-update script (scripts/auto-update/version-in-file.sh) only updates English files listed in all-versions.sh. Localized files (ja, zh, etc.) that have the same frontmatter version variables drift behind over time.

This PR adds an update_locale_files() function to version-in-file.sh that, after updating each English file under content/en/, automatically discovers and updates locale equivalents via a content/*/ glob. It silently skips locales where the file doesn't exist or lacks the relevant variable.

Footnotes

1. Yes, I can answer maintainer questions about the content of this PR, without using AI. ↩

[Copilot]

Pull request overview

Adds locale-awareness to the existing version auto-update automation so that localized content/*/ pages stay in sync with the version frontmatter variables maintained in the English sources under content/en/.

Changes:

• Introduces update_locale_files() to discover locale equivalents for updated English content files and update matching version variables.
• Invokes locale updates after each process_file run, skipping missing locale files or files without the target variable.