fix(scripts): run_tests_batched.py stdout UTF-8 (fix UnicodeEncodeError crash at line 185)

Phase 13.1. The test runner script crashed on UnicodeEncodeError at line 185
(the summary table print). Without this fix, the test suite cannot run to
completion. Fix: sys.stdout.reconfigure(encoding='utf-8', errors='replace')
at the start of main(). This is the FIRST action of Phase 13 -- without it,
no other test verification is possible.

The crash was triggered by box-drawing characters (U+2502 etc.) in the
summary table being printed to a Windows console using cp1252 encoding.
The reconfigure enables UTF-8 output on Windows and is a no-op on
Linux/macOS where stdout is already UTF-8 by default.

scripts/run_tests_batched.py

@@ -207,6 +207,14 @@ def _print_summary(results: list[tuple[Batch, int, float]]) -> int:
  return worst
 
 def main() -> int:
+ try:
+  sys.stdout.reconfigure(encoding="utf-8", errors="replace")
+ except Exception:
+  pass
+ try:
+  sys.stderr.reconfigure(encoding="utf-8", errors="replace")
+ except Exception:
+  pass
  p = argparse.ArgumentParser()
  p.add_argument("--tests-dir",      default=str(_PROJECT_ROOT / "tests"))
  p.add_argument("--registry",       default=str(_PROJECT_ROOT / "tests" / "test_categories.toml"))