dsh-pc-bridge: Open a loopback HTTP bridge for a trusted peer

dsh-pc-bridge is a DeepSeek Harness plugin that opens a small HTTP bridge on a machine listening exclusively on the loopback interface, allowing the cloud endpoint to ping this machine and execute shell commands on demand, optionally maintaining an SSH reverse tunnel. Maintained by QIC-9821, it is categorized as a networking utility, licensed under MIT, has no third-party runtime dependencies, and requires Node.js ≥ 22. It provides two tools, pc_ping and pc_exec, each of which requires the x-pc-secret header; the key is sourced from environment variables or a key file, and logs do not record the key value. The README explicitly states that it provides arbitrary command execution capabilities, so the key should only be entrusted to trusted endpoints, and listenHost should not be changed to 0.0.0.0.