refactor(node_compat): extract report module and deduplicate PTY/piped paths

- Move all report-related types (TestReport, ErrorInfo, ResultInfo,
  CollectedResult) and functions (generate_report, get_deno_version,
  read_node_version) into a separate `report` module.

- Extract TestSetup struct that computes shared state (args, env vars,
  timeout, flags) once, then both run_piped() and run_pty() consume it.
  This eliminates the duplicated command-building logic between the two
  execution paths.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: bartlomieju