Add benchmarks using Criterion for:
- XML tool-call parsing (single and multi-call)
- Native tool-call parsing
- SQLite memory store/recall/count operations
- Full agent turn cycle (text-only and with tool call)
Add CI workflow (.github/workflows/benchmarks.yml) that:
- Runs benchmarks on push to main and on PRs
- Uploads Criterion results as artifacts
- Posts benchmark summary as PR comment for regression visibility
Ref: https://github.com/zeroclaw-labs/zeroclaw/issues/618 (item 7)
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
