Update CHANGELOG.md with recent changes

Updated changelog to remove fixed section and add new entries.

Author: brendan-kellam

CHANGELOG.md

@@ -28,8 +28,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Passed Zoekt index parameters via argv to preserve revision names with punctuation. [#1376](https://github.com/sourcebot-dev/sourcebot/pull/1376)
 - [EE] Validated OAuth bearer token scopes before allowing access to the Sourcebot MCP resource server. [#1396](https://github.com/sourcebot-dev/sourcebot/pull/1396)
 - Added HTTP security headers to all web app responses. [#1407](https://github.com/sourcebot-dev/sourcebot/pull/1407)
-
-### Fixed
 - Upgraded `nodemailer` to `^9.0.1`. [#1356](https://github.com/sourcebot-dev/sourcebot/pull/1356)
 
 ## [5.0.4] - 2026-06-18