- Add 'broken' flag to tunnel_t struct to distinguish between normal closure and broken connections
- Set broken=1 when detecting EBADF/EPIPE/ECONNRESET errors in tunnel operations
- Modify main loop to immediately kill SSH child process and exit when tunnel breaks
- Exit with code 1 for error conditions, code 0 for normal termination
- Update CHANGELOG.md, README.md, and TODO.md for version 1.4.7
- Prevent indefinite hanging of wsssh process after tunnel failures