Only send de-indexed URLs once.

[peterwilsoncc]

Ensure that deindexed URLs are only pinged once unless they subsequently become a redirect or similar.

Fixes #15.

[Copilot]

Pull Request Overview

Adds logic to only re-ping the most recently deindexed (previous) URL plus the current permalink, and introduces a helper to retrieve the last pinged URL. Updates ping URL storage to preserve insertion order and avoid duplicate re-pings, and adds tests to cover slug/status transitions and append behavior.

• Introduces get_last_post_ping_url and changes ping_indexnow to send only the previous plus current URL.
• Revises add_post_ping_urls to control ordering and duplication behavior.
• Adds multiple new test cases for slug changes, status transitions, and ping URL list updates.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
inc/namespace.php	Adds last ping URL helper and adjusts ping URL aggregation logic.
tests/class-test-indexnow-pings.php	Adds test coverage for deindexing, slug/status transitions, and URL list ordering.

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}