- Replace legacy entrypoint with the current build/ version
(PTY_TOOL support, init/manage/attach/run commands, SIGTERM trap,
port-readiness liveness check, abduco session detection, <container>
placeholder in error messages); only difference is binary name
protonmail-bridge instead of /protonmail/proton-bridge
- Add ARG/ENV PTY_TOOL and conditional apt install of dtach/abduco/reptyr
- Add HEALTHCHECK on 127.0.0.1 for all four ports (25, 143, 1025, 1143)
- Switch from CMD bash ... to ENTRYPOINT + CMD ["run"]
