When get_localzone_name() returns None, the server now defaults to UTC
instead of raising an error. This makes the server more robust in
environments where the local timezone cannot be determined.
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).
