* fix(xray): validate panel egress target
Avoid generating a loopback panel bridge and routing rule when a saved panel outbound disappears after an outbound subscription refresh. Preserve routing unchanged and log the missing target instead.
* fix(xray): guard node and mtproto egress
Apply the fail-closed target check to every generated egress bridge. Skip node and MTProto bridge injection when a selected outbound disappears or the relevant JSON cannot be parsed.
* test(xray): complete node egress coverage
Cover tag and port collisions plus absent and malformed routing. Clarify the fail-closed bridge behavior in the panel and MTProto egress documentation.
