Add triage tests, prepare-export, and UI fixes for Levkin migration.

Cherry-pick heuristics, manifest merge, global file search, scrollbar styling, and pytest/Playwright coverage unblock review and filtered export for mmetl.

tests/test_preset_skips.py

@@ -0,0 +1,50 @@
+"""Tests for scripts/preset-skips.py."""
+
+from __future__ import annotations
+
+import importlib.util
+import json
+from pathlib import Path
+
+import pytest
+
+REPO = Path(__file__).resolve().parents[1]
+
+
+def _load_preset_skips():
+    path = REPO / "scripts" / "preset-skips.py"
+    spec = importlib.util.spec_from_file_location("preset_skips", path)
+    mod = importlib.util.module_from_spec(spec)
+    assert spec.loader
+    spec.loader.exec_module(mod)
+    return mod
+
+
+def test_load_preset_tiers():
+    mod = _load_preset_skips()
+    preset = mod.load_preset(REPO / "presets" / "levkin-skips.json")
+    assert "medical" in preset["skip_all"]
+    assert "zoey" in preset["review_priority"]
+    assert "29wilson" in preset["tier_b"]
+
+
+def test_channel_entry_skip():
+    mod = _load_preset_skips()
+    entry = mod.channel_entry_skip("tier-a")
+    assert entry["status"] == "skip"
+    assert entry["reviewed"] is True
+
+
+def test_main_writes_manifest(tmp_path, fixture_export_path, monkeypatch):
+    mod = _load_preset_skips()
+    manifest_path = tmp_path / "manifest.json"
+    monkeypatch.setattr(mod, "MANIFEST_PATH", manifest_path)
+    monkeypatch.setattr(mod, "DEFAULT_EXPORT", fixture_export_path)
+
+    import sys
+
+    sys.argv = ["preset-skips.py", str(fixture_export_path)]
+    assert mod.main() == 0
+    data = json.loads(manifest_path.read_text())
+    assert data["channels"]["medical"]["status"] == "skip"
+    assert "zoey" not in data["channels"] or data["channels"].get("zoey", {}).get("status") != "skip"