docs: changelog entry for configurable docker host ports

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -18,6 +18,12 @@ collide with the per-component `api-v…` / `ui-v…` tags in this monorepo.
 
 ## [Unreleased]
 
+### Changed
+- Docker host ports are now configurable via `API_PORT` / `UI_PORT` in
+  `.env` (defaults `8081` / `8080`). Container-internal ports remain
+  fixed, so internal docker DNS, healthchecks, and baked Caddyfiles are
+  unchanged — only the published host-side mapping moves.
+
 ## [0.9] — 2026-05-06
 
 First public preview of the bundled stack. Everything specified in