chore: rename report directory in gitignore

Update .copilot_reports/ to .agent_reports/ for consistency.

Signed-off-by: umatare5 <umatare5@gmail.com>
AI-assisted-by: GitHub Copilot Coding Agent

Author: umatare5

.gitignore

@@ -24,7 +24,7 @@ coverage/*
 
 # IDE files
 .idea/
-.copilot_reports/
+.agent_reports/
 *.swp
 *.swo
 .env