Clarify diagnostic language and explanations

tests/test_health.py

@@ -58,6 +58,8 @@ def test_empty_library_has_no_health_score():
     assert report.score is None
     assert report.total_references == 0
     assert report.scored_references == 0
+    assert not report.database_present
+    assert report.tracks_missing_from_database == 0
 
 
 def test_smart_crate_references_are_reported_but_not_scored():

tests/test_web.py

@@ -23,6 +23,8 @@ def test_web_analysis_uses_production_health_pipeline(tmp_path):
     assert result["smart_crates"] == 2
     assert result["database_entries"] == 10
     assert result["database_library_matches"] == 10
+    assert result["database_missing_paths"] == 0
+    assert result["database_missing_unique_filenames"] == 0
     assert result["tracks_missing_from_database"] == 0
 
 
@@ -36,3 +38,7 @@ def test_web_static_assets_are_declared_and_packaged():
 
     assert set(STATIC_FILES) == {"/", "/app.css", "/app.js"}
     assert all((asset_root / filename).is_file() for filename, _ in STATIC_FILES.values())
+    html = (asset_root / "index.html").read_text(encoding="utf-8")
+    assert "Missing tracks in Serato" in html
+    assert "Old crate references" in html
+    assert html.count('class="info-button"') >= 10