[Feature] Display `event_time` in model details panel

## Summary

Display the `event_time` configuration in the model details panel of the dbt docs UI. This is important for developers working with microbatch models who need to verify that `event_time` is configured on a model and its parents.

## Context

Originally filed as [dbt-labs/dbt-core#12800](https://github.com/dbt-labs/dbt-core/issues/12800). The issue author confirmed it's a docs UI feature request — `event_time` is already present in the manifest at `node.config.event_time`, so no `dbt-core` changes are needed. This is a frontend-only change in `dbt-docs`.

## Proposed Change

Add an `event_time` row to the `getBaseStats()` function in `src/app/components/table_details/table_details.js`, following the same pattern as other config properties (Owner, Type, Language, Contract, etc.). The row should only display when `event_time` is configured (non-null).

## Who will this benefit?

Developers working on microbatch models who need to validate `event_time` expectations for the parents of the model they're working on, without having to check both the YAML and the code manually.