fix: handle socket close errors properly in PapertrailLogHandler

- Replace contextlib.suppress with try/except + warning log
- Add test for fail2ban client
- Remove stale Issue #21 from Tasks.md (indexes)

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

backend/tests/test_services/test_fail2ban_client.py

@@ -214,6 +214,38 @@ class TestCoerceCommandToken:
         assert _coerce_command_token(None) == "None"
 
 
+class TestSendCommandSyncCloseError:
+    """Tests for socket close error handling in :func:`_send_command_sync`."""
+
+    def test_close_error_is_logged_but_not_reRaised(self) -> None:
+        """close() raising must log a warning, not mask the original error."""
+        fake_client = MagicMock()
+        fake_client.send.return_value = [0, "ok"]
+        fake_client.close.side_effect = RuntimeError("close failed")
+        fake_cls = MagicMock(return_value=fake_client)
+
+        with (
+            patch(
+                "app.utils.fail2ban_client._load_vendored_fail2ban_client",
+                return_value=fake_cls,
+            ),
+            patch("app.utils.fail2ban_client.log") as mock_log,
+        ):
+            result = _send_command_sync(
+                socket_path="/fake/fail2ban.sock",
+                command=["status"],
+                timeout=1.0,
+            )
+
+        assert result == [0, "ok"]
+        warning_calls = [
+            c for c in mock_log.warning.call_args_list
+            if c[0][0] == "fail2ban_socket_close_error"
+        ]
+        assert len(warning_calls) == 1
+        assert warning_calls[0][1]["error"] == "close failed"
+
+
 # ---------------------------------------------------------------------------
 # Extended tests for Fail2BanClient.send
 # ---------------------------------------------------------------------------