fix(scripts): stop setup-tasks text mode crashing on a legacy code page (#3892)

_check_file/_check_dir hard-code U+2713/U+2717 and print() them to
sys.stdout. On Windows sys.stdout falls back to the ANSI code page whenever
stdout is not a console — which is every time an agent or a workflow step
captures the output — and U+2713 is unencodable in cp1252, so the document
listing aborted mid-report with UnicodeEncodeError.

This is the byte-identical twin of the block in
scripts/python/check_prerequisites.py, which I flagged in the PR for that
file rather than widening its scope.

Fall back to ASCII when stdout cannot encode the glyph. "[OK]"/"[FAIL]" is
the rendering these markers already have in-tree: Test-FileExists in
scripts/powershell/common.ps1 emits exactly those, and
normalize_status_text in tests/parity_helpers.py maps the glyphs onto them.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/python/setup_tasks.py

@@ -55,14 +55,31 @@ def _available_docs(paths: FeaturePaths) -> list[str]:
     return docs
 
 
+def _status_marker(ok: bool) -> str:
+    """Return the status glyph, downgraded to ASCII when stdout cannot encode it.
+
+    On Windows sys.stdout falls back to the ANSI code page whenever it is not a
+    console - a pipe or a file redirect, which is how agents and workflow steps
+    invoke these scripts - and U+2713 is unencodable in cp1252, so printing it
+    raised UnicodeEncodeError and aborted the report mid-listing.
+    "[OK]"/"[FAIL]" is the ASCII rendering these markers already have in-tree:
+    see Test-FileExists in scripts/powershell/common.ps1 and
+    normalize_status_text in tests/parity_helpers.py.
+    """
+    glyph = "✓" if ok else "✗"
+    try:
+        glyph.encode(getattr(sys.stdout, "encoding", None) or "utf-8")
+    except (LookupError, UnicodeEncodeError):
+        return "[OK]" if ok else "[FAIL]"
+    return glyph
+
+
 def _check_file(path: Path, description: str) -> None:
-    marker = "✓" if path.is_file() else "✗"
-    print(f"  {marker} {description}")
+    print(f"  {_status_marker(path.is_file())} {description}")
 
 
 def _check_dir(path: Path, description: str) -> None:
-    marker = "✓" if _dir_has_entries(path) else "✗"
-    print(f"  {marker} {description}")
+    print(f"  {_status_marker(_dir_has_entries(path))} {description}")
 
 
 def main(argv: list[str] | None = None) -> int: