Remove the one-time env-to-config migration from the settings

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,13 @@
 All notable changes to CodeCraft. Versions follow [Semantic Versioning](https://semver.org/);
 until 1.0, minor versions may contain breaking changes.
 
+## [Unreleased]
+
+### Removed
+
+- *Settings → Config file* no longer offers to move `${NAME}` values into the configuration (a
+  one-time migration); `${NAME}` references keep working.
+
 ## [v202611-00002] – 2026-11-09
 
 ### Added