Remove accidental .venv commit; add .gitignore; keep Copilot instructions

Author: maple-underscore

.gitignore

@@ -0,0 +1,24 @@
+# Python
+__pycache__/
+*.py[cod]
+*.pyo
+*.pyd
+
+# Virtual environments
+.venv/
+venv/
+.env/
+
+# macOS
+.DS_Store
+
+# Logs and local outputs
+logs/
+arrasbot.log
+
+# Editor
+.vscode/
+.idea/
+
+# Cache
+*.cache/