Add a new utility tool to get current time/date with the following features:
- Multiple output formats: iso, time, date, datetime, unix
- Timezone support (e.g., UTC, America/New_York, Asia/Shanghai)
- Configurable via PICOCLAW_TOOLS_GET_CURRENT_TIME_ENABLED env var
- Web UI support with utility category and i18n translations
The tool is registered in the agent tool registry and can be enabled/disabled
via configuration or web interface.
