Add ExpressionEngine 7.5.27 release changelog

[TomJaeger]

Overview

Adds the ExpressionEngine 7.5.27 changelog for the planned September 21, 2026 release, retaining the important security updates notice and including contributor credits, bug fixes, and developer changes from the milestone's open and merged PRs and the release comparison.

A source-only release preparation note identifies the four planned fixes (#5373, #5391, #5398, and #5400) whose inclusion and contributor credits should be confirmed before publication. Previous release entries are unchanged.

Nature of This Change

• 🐛 Fixes a bug
• 🚀 Implements a new feature
• 🛁 Rewrites existing documentation
• 💅 Fixes coding style
• 🔥 Removes unused files / code

Related Application Change

Application Pull Request: ExpressionEngine/ExpressionEngine#5405

Milestone: https://github.com/ExpressionEngine/ExpressionEngine/pulls?q=is%3Apr+milestone%3A7.5.27

Validation

• npm run build passed with 74 unrelated existing documentation link warnings; no changelog link warnings.
• git diff --check passed.
• Verified the Monday release date, security notice rendering, contributor credits, milestone PR references, and unchanged previous release entries.
• Self-review found no remaining actionable issues.