fix(bitlesson): restore haiku as Claude agent model in bitlesson-selector frontmatter

Author: Rubiczhang

agents/bitlesson-selector.md

@@ -1,7 +1,7 @@
 ---
 name: bitlesson-selector
 description: Selects required BitLesson entries for a specific sub-task. Use before execution for every task or sub-task.
-model: gpt-5.2
+model: haiku
 tools: Read, Grep
 ---