Resolves conflicts: take HEAD (security audit) for mcp.rs imports,
register_server_blocking error handling, and maybe_execute_tools loop.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Add anyllm_batch_engine dependency to proxy Cargo.toml
- Add batch_engine field to AppState (Option<Arc<BatchEngine<...>>>)
- Add POST /v1/batches/{batch_id}/cancel route and handler
- cancel_batch handler uses BatchEngine when available, falls back to not_implemented