9a2cc3bda0
- Added `cwd` and `env` optional parameters to kernel execution API for runtime working directory and environment variable control. - Implemented runtime environment setup in Python runner with `_apply_request_runtime()` to apply cwd and env from request before code execution. - Enhanced SIGINT handler management with `active_executions` counter and `_begin_exec_sigint()` / `_end_exec_sigint()` functions to prevent state mutation during concurrent execution. - Changed `SearchRenderArgs.paths` parameter type from `string[]` to `string | string[]` to accept single string paths. - Added comprehensive test coverage for kernel cwd updates, timeout interruption safety, and SystemExit handling in shared executor sessions.