Update What's new navigation item render behavior

Roy Liurequested to merge
561510-update-what-s-new-navigation-item-render-logic into master

What does this MR do and why?

This MR:

  1. fixes #561510 (closed) by moving away from using localStorage
  2. implements #563433 (closed) so the What's new sidebar navigation item remains until all articles are read, and the count remains updated with actual unread articles.

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Screen_Recording_2025-09-03_at_12.32.19_PM

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Related to #561510 (closed)

Edited by Roy Liu

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