docs: update CHANGELOG and PROJECT.md for CMS admin improvement

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -6,6 +6,18 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Unreleased]
 
+### Added
+- **CMS admin improvement** — articles list now has HTMX filter bar (search,
+  status, template, language), pagination (50/page), and stats strip
+  (total/live/scheduled/draft counts). Article actions (publish/unpublish,
+  delete) are inline HTMX operations — no full page reload. "View" link opens
+  live articles on the public site. Article generation and rebuild-all now
+  enqueue to the background worker instead of blocking the HTTP request.
+  Markdown source is written to disk during generation so the edit form shows
+  content. Sitemap cache is invalidated when articles are published, deleted,
+  or created. Fixed broken "Scheduled"/"Published" status display (was always
+  showing "Scheduled") and stale `template_data_id` column reference.
+
 ### Changed
 - **Visual test overhaul** — consolidated 3 separate Playwright server processes
   (ports 5111/5112/5113) into 1 session-scoped fixture in `conftest.py`; 77 tests