test: make metrics_path fallback assertion Windows-safe

\`str(Path.home() / \".geno-lewm\" / \"logs\" / \"metrics.prom\")\` produces
backslash-separated output on Windows, so the previous
\`.endswith(\".geno-lewm/logs/metrics.prom\")\` assertion failed there.
Compare path components via \`.parts\` instead; the check is identical
on POSIX and works on Windows.

Author: claude

tests/unit/test_coverage_extras.py

@@ -93,8 +93,10 @@ def test_exporter_default_path_uses_env(monkeypatch: pytest.MonkeyPatch, tmp_pat
 def test_metrics_path_falls_back_to_home(monkeypatch: pytest.MonkeyPatch) -> None:
     monkeypatch.delenv("GENO_LEWM_LOG_DIR", raising=False)
     p = m.metrics_path()
+    # Compare path components so the test holds on Windows
+    # (backslashes) as well as POSIX (forward slashes).
     assert p.name == "metrics.prom"
-    assert str(p).endswith(".geno-lewm/logs/metrics.prom")
+    assert p.parts[-3:] == (".geno-lewm", "logs", "metrics.prom")
 
 
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