psc-1944_add-codeowner-check-action

[harshil-roo]

JIRA: PSC-1944

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Why this PR?

We're adding a CI/CD check to automatically validate your CODEOWNERS file on every commit.

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The Problem

Invalid or misconfigured CODEOWNERS files can cause:

• Missed or incorrect code reviews
• Security gaps (anyone with write access can approve PRs)
• Slower workflows (missed team notifications)
• Audit issues (large or broken codeowner groups)

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The Solution

A new CI check will:

• Warn if your CODEOWNERS file is missing or invalid
• Check that all listed teams/users exist and have write access

For now, this is a warning only.
We’ll make it blocking soon.

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What to Do

1. Approve this PR, even if you see a warning.
2. Review your CODEOWNERS file and fix any issues. Confirm this PR is either updating an existing codeowners file or adding a new one.
3. Make sure your codeowners meet GitHub Security Standard.

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For help, ask in #support-devsecops.