chore: ignore runtime config files and reorganize .gitignore

- Ignore *.yaml and *.yaml.backup files
- Reorganize sections with clear comments

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.gitignore

@@ -25,4 +25,11 @@ test-*.js
 compare_*.js
 
 # logs
-logs
+logs
+
+# oh my opencode
+.sisyphus
+
+# Runtime config files
+*.yaml
+*.yaml.backup