Logs messages from `entrypoint.sh` and the other `run-*.sh` scripts
don't show timestamp today, and its getting hard to see the order of
things in the logs, especially between different processes.
This PR adds a command `tlog` to print logs with UTC timestamp prefixed.
We're only using it in `entrypoint.sh` now, but follow-up PR(s) will add
it to the other `run-*` scripts as well.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
- **Chores**
- Updated Dockerfile to include `/opt/bin` in the `PATH` and modified
permissions settings for executable files.
- **Refactor**
- Enhanced logging in the entrypoint script by replacing `echo`
statements with `tlog` for better clarity and debugging.
- **New Features**
- Introduced `tlog`, a new shell script for consistent and timestamped
logging.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
