Draft changelog: Ads API campaign budget optimization

[mintlify]

Summary

Adds a weekly changelog entry for the X Ads API change that simplifies campaign budget optimization to LINE_ITEM.

Changes

• New Jun 28, 2026 entry under X Ads API in changelog.mdx.
• Notes budget_optimization now accepts only LINE_ITEM (also the new default) on campaign create/update.
• Notes standard_delivery is deprecated at the campaign level and should be set on the line item.
• Links to the Campaign Management reference for full details.

Context

Based on the only product-affecting PR merged since the previous changelog entry (Jun 11, 2026): #211.

[mintlify]

Preview deployment for your docs. Learn more about Mintlify Previews.

Project	Status	Preview	Updated (UTC)
x-corp	🟢 Ready	View Preview	Jun 28, 2026, 10:36 PM

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}