Release v1.8.0

Promote CHANGELOG [Unreleased] to [1.8.0].

AI-Local-Session: 461e0a61-a892-44b3-897d-e4d2d37f1142
AI-Cloud-Session: 7ea21bb1-fbcf-4d33-a5f9-438a3a76b475
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Geeven Singh

CHANGELOG.md

@@ -12,6 +12,8 @@ body. Keep section headings exact and write notes in Markdown.
 
 ## [Unreleased]
 
+## [1.8.0] - 2026-06-06
+
 ### Added
 
 - **Markdown rendered-diff view.** When viewing `.md` or `.markdown`