feat(system): report health problems and keep recent log entries

tests/test_import_flow.py

@@ -1328,3 +1328,34 @@ def test_adopt_files_already_in_the_library(client):
     assert (root / "Tolkien/Der Hobbit/01.mp3").exists()  # nothing moved
     assert client.get(f"/api/import/library/{lib}").json()["items"] == []
     assert [h["event"] for h in client.get("/api/history").json()] == ["adopted"] * 2
+
+
+def test_health_reports_problems_as_codes(client, monkeypatch):
+    from wordarr import connect
+    from wordarr.metadata import hardcover
+    monkeypatch.setattr(hardcover, "TOKEN", "")
+    monkeypatch.setattr(connect, "ABS_URL", "http://abs")
+    monkeypatch.setattr(connect, "ABS_TOKEN", "")
+    gone = client.tmp_path / "gone"
+    client.post("/api/libraries", json={
+        "name": "Weg", "media_type": "ebook", "root_path": str(gone)})
+    client.post("/api/libraries", json={
+        "name": "Da", "media_type": "ebook", "root_path": str(client.downloads)})
+
+    issues = client.get("/api/system/health").json()
+    assert {(i["code"], i.get("name")) for i in issues} == {
+        ("library.missing", "Weg"), ("hardcover.token", None), ("abs.incomplete", None)}
+
+    monkeypatch.setattr(hardcover, "TOKEN", "x")
+    monkeypatch.setattr(connect, "ABS_URL", "")
+    gone.mkdir()
+    assert client.get("/api/system/health").json() == []
+
+
+def test_recent_logs_newest_first(client):
+    import logging
+    logging.getLogger("wordarr.test").info("first")
+    logging.getLogger("wordarr.test").warning("second")
+    rows = client.get("/api/system/logs").json()
+    assert [r["message"] for r in rows[:2]] == ["second", "first"]
+    assert rows[0]["level"] == "WARNING"