fix(ci): keep install-docs help cp1252-safe

scripts/validate-install-docs.py

@@ -13,7 +13,7 @@ Markers:
 
 Normalisation (per RESEARCH Pitfall #4):
   - rstrip trailing whitespace
-  - normalise CRLF → LF
+  - normalise CRLF -> LF
   - strip `$ ` and `>>> ` REPL/prompt prefixes
   - skip blank lines + lines that are only `#` comments
 

tests/scripts/test_validate_install_docs.py

@@ -21,6 +21,8 @@ the tests don't depend on the real repo state.
 from __future__ import annotations
 
 import importlib.util
+import os
+import subprocess
 import sys
 from pathlib import Path
 
@@ -52,6 +54,19 @@ def _make_root(tmp_path: Path, *, docs: dict[str, str], script: str) -> Path:
     return tmp_path
 
 
+def test_help_is_safe_for_cp1252_consoles():
+    env = os.environ.copy()
+    env["PYTHONIOENCODING"] = "cp1252"
+    result = subprocess.run(
+        [sys.executable, str(SCRIPT_PATH), "--help"],
+        check=False,
+        capture_output=True,
+        env=env,
+    )
+
+    assert result.returncode == 0, result.stderr.decode("ascii", errors="replace")
+
+
 def test_clean_state_passes(validator_module, tmp_path, capsys):
     root = _make_root(
         tmp_path,