feat: add model comparisons and sanitize session files

- Rename gamma to glm5 and model to minimax-m2.7
- Add model_comparison/ directory with head-to-head analyses
- Sanitize all session.jsonl files: remove absolute paths and usernames
- Remove __pycache__ artifacts
- Add .gitignore

.gitignore

@@ -0,0 +1,18 @@
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+
+# macOS
+.DS_Store
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# Session backups
+*.jsonl.bak