muster release v5.29.4

kubectl logs shows muster’s log when an OTLP endpoint is set. In OTLP mode mcp-toolkit’s logging replaced the console handler, so muster wrote nothing to stdout or stderr, and with the collector down its log went nowhere. muster serve now passes mcp-toolkit’s WithStderrMirror in OTLP mode: every record also goes to stderr as JSON with trace_id and span_id. --silent still writes nothing to the console. (giantswarm/giantswarm#36711)