Replaced local timezone detection using tzinfo string (e.g. "CEST")
with tzlocal.get_localzone_name() to ensure a valid IANA time zone
(e.g. "Europe/Paris") is passed to ZoneInfo. This avoids runtime
errors on macOS and other systems that return non-IANA tz abbreviations.
Fixes#639
Add support for configurable timezone in Docker for `time` server.
* Update `src/time/Dockerfile` to include `LOCAL_TIMEZONE` environment variable.
* Set default timezone to "UTC" in `src/time/Dockerfile`.
* Modify `ENTRYPOINT` in `src/time/Dockerfile` to include `--local-timezone` argument.
* Update `src/time/README.md` to include instructions on setting the timezone using `LOCAL_TIMEZONE` environment variable.
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For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/modelcontextprotocol/servers/issues/639?shareId=XXXX-XXXX-XXXX-XXXX).
