epa4all-client: Unauthenticated REST API for Patient Record Writes

epa4all-client is the Java Client for epa4all / ePA 3.0 in the Telematik Infrastruktur. In 1.2.4 and earlier, any network-reachable caller can write arbitrary documents to any patient's electronic health record accessible by the institution's SMC-B card. In a misconfigured deployment (e.g., following the production Docker example in the README), this is exploitable from the local network without credentials.