Add /clear command

Co-Authored-By: Claude Sonnet 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]
+
+### Added
+
+- **`/clear`**: the model forgets the conversation so far; the chat keeps showing it, a divider marks
+  the cut. Also starts a fresh session with Claude Code.
+
 ## [v202611-00029] – 2026-11-15
 
 ### Added