feat: comprehensive health check with DB, scheduler, cache

- Add /api/v1/health endpoint with component-level checks
- Verify DB connectivity, fail2ban socket, scheduler, session cache
- Add SQLite WAL cleanup on startup (orphan crash files)
- Migration 8: import_log.timestamp → INTEGER UNIX epoch
- Align import_log timestamps with history_archive (already UNIX int)
- Add unit tests for DB cleanup and health router

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/tests/test_routers/test_health.py

@@ -8,15 +8,14 @@ from app.models.server import ServerStatus
 
 @pytest.mark.asyncio
 async def test_health_check_returns_200_when_online(client: AsyncClient) -> None:
-    """``GET /api/health`` must return HTTP 200 when fail2ban is online."""
-    client._transport.app.state.server_status = ServerStatus(online=True)
+    """``GET /api/v1/health`` must return HTTP 200 when fail2ban is online."""
     response = await client.get("/api/v1/health")
     assert response.status_code == 200
 
 
 @pytest.mark.asyncio
 async def test_health_check_returns_503_when_offline(client: AsyncClient) -> None:
-    """``GET /api/health`` must return HTTP 503 when fail2ban is offline."""
+    """``GET /api/v1/health`` must return HTTP 503 when fail2ban is offline."""
     client._transport.app.state.server_status = ServerStatus(online=False)
     response = await client.get("/api/v1/health")
     assert response.status_code == 503
@@ -24,27 +23,84 @@ async def test_health_check_returns_503_when_offline(client: AsyncClient) -> Non
 
 @pytest.mark.asyncio
 async def test_health_check_returns_ok_status_when_online(client: AsyncClient) -> None:
-    """``GET /api/health`` must contain ``status: ok`` when fail2ban is online."""
-    client._transport.app.state.server_status = ServerStatus(online=True)
+    """``GET /api/v1/health`` must contain ``status: ok`` when fail2ban is online."""
     response = await client.get("/api/v1/health")
-    data: dict[str, str] = response.json()
+    data: dict[str, object] = response.json()
     assert data["status"] == "ok"
     assert data["fail2ban"] == "online"
 
 
 @pytest.mark.asyncio
 async def test_health_check_returns_unavailable_when_offline(client: AsyncClient) -> None:
-    """``GET /api/health`` must contain ``status: unavailable`` when fail2ban is offline."""
+    """``GET /api/v1/health`` must contain ``status: unavailable`` when fail2ban is offline."""
     client._transport.app.state.server_status = ServerStatus(online=False)
     response = await client.get("/api/v1/health")
-    data: dict[str, str] = response.json()
+    data: dict[str, object] = response.json()
     assert data["status"] == "unavailable"
     assert data["fail2ban"] == "offline"
 
 
 @pytest.mark.asyncio
 async def test_health_check_content_type_is_json(client: AsyncClient) -> None:
-    """``GET /api/health`` must set the ``Content-Type`` header to JSON."""
+    """``GET /api/v1/health`` must set the ``Content-Type`` header to JSON."""
     response = await client.get("/api/v1/health")
     assert "application/json" in response.headers.get("content-type", "")
 
+
+@pytest.mark.asyncio
+async def test_health_check_includes_database_status(client: AsyncClient) -> None:
+    """``GET /api/v1/health`` must include database status field."""
+    response = await client.get("/api/v1/health")
+    data: dict[str, object] = response.json()
+    assert "database" in data
+    assert data["database"] in ("ok", "error")
+
+
+@pytest.mark.asyncio
+async def test_health_check_includes_scheduler_status(client: AsyncClient) -> None:
+    """``GET /api/v1/health`` must include scheduler status field."""
+    response = await client.get("/api/v1/health")
+    data: dict[str, object] = response.json()
+    assert "scheduler" in data
+    assert data["scheduler"] in ("running", "stopped", "unknown")
+
+
+@pytest.mark.asyncio
+async def test_health_check_includes_cache_status(client: AsyncClient) -> None:
+    """``GET /api/v1/health`` must include cache status field."""
+    response = await client.get("/api/v1/health")
+    data: dict[str, object] = response.json()
+    assert "cache" in data
+    assert data["cache"] in ("initialised", "uninitialised")
+
+
+@pytest.mark.asyncio
+async def test_health_check_includes_components_list(client: AsyncClient) -> None:
+    """``GET /api/v1/health`` must include components list."""
+    response = await client.get("/api/v1/health")
+    data: dict[str, object] = response.json()
+    assert "components" in data
+    assert isinstance(data["components"], list)
+
+
+@pytest.mark.asyncio
+async def test_health_check_offline_adds_fail2ban_to_components(
+    client: AsyncClient,
+) -> None:
+    """When fail2ban is offline, it must appear in the components list."""
+    client._transport.app.state.server_status = ServerStatus(online=False)
+    response = await client.get("/api/v1/health")
+    data: dict[str, object] = response.json()
+    assert data["status"] == "unavailable"
+    components: list[dict[str, object]] = data["components"]  # type: ignore[assignment]
+    assert any(c.get("name") == "fail2ban" and c.get("healthy") is False for c in components)
+
+
+@pytest.mark.asyncio
+async def test_health_check_online_returns_empty_components(client: AsyncClient) -> None:
+    """When all components are healthy, components list must be empty."""
+    response = await client.get("/api/v1/health")
+    data: dict[str, object] = response.json()
+    assert data["status"] == "ok"
+    assert data["components"] == []
+