44649e69f4
Addresses hermes-sweeper review on PR #54866: the installer runs tools/skills_sync.py as a child python.exe whose PYTHONIOENCODING / PYTHONUTF8 the scoped install.ps1 block sets, but there was no regression test for this child-Python UTF-8 path. The existing test_child_process_inherits_utf8_mode covers a different (bootstrap entry-point) flow. Add TestSkillsSyncUtf8Guard: three subprocess tests that import skills_sync (triggering its import-time stdout/stderr reconfigure) and assert the checkmark/up-arrow glyphs the script prints at tools/skills_sync.py:596,675 emit valid UTF-8 and exit 0 even when the child env is left unset or explicitly hostile (gbk). A third test proves the guard is load-bearing by reproducing the crash without it. Also keep the new install.ps1 comment ASCII-only (the checkmark spelled out as U+2713) per the file's PS 5.1 parser-compatibility contract at scripts/install.ps1:79-80; the literal glyph in the comment violated that contract.