Send-command is broken

Image: itzg/minecraft-bedrock-server (latest)
Host: Ubuntu 24.04 x86_64
Docker: official package (not Snap)

Problem:
send-command always fails with:

find: '/proc//exe': Permission denied
ERROR: failed to search for bedrock server process

Observations:
- docker attach works normally
- bedrock_server is running
- /proc//exe cannot be resolved even from inside the container
- writing to /proc//fd/0 also fails with Permission denied
- send-command relies on scanning /proc/*/exe

Start by locating and running the send-command entry point, then reproduce the failure in the reported Ubuntu 24.04 Docker environment. Trace its scan of /proc/*/exe and attempts to use /proc//fd/0, using docker attach as the working comparison; done means send-command can target the running Bedrock server despite the permission restrictions.

Written by the indexing model from the issue text.