Add replace-tool-args.audit.test.ts that scans src/**/*.ts for direct
output.args property assignments and Object.assign(output.args, ...) outside
the helper. Also fix the 9th mutation site discovered by the audit in
compaction-todo-preserver/hook.ts.
Add replace-tool-args.test.ts with 12 regression tests covering both mutable
and Object.freeze'd output.args scenarios for all hook patterns.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
YeonGyu-Kim