## Context
Saves the last visited explorer tab via `useDashboardHistory`, such that
landing back on `/explorer` will open the last visited page. Similar
behaviour to Table Editor and SQL Editor
Would also be useful when going between the SQL Editor and Explorer to
bring snippets over
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **New Features**
* Explorer now remembers and restores the last visited query, chat, or
notebook tab.
* Automatically returns to the Explorer home screen when a saved tab is
unavailable.
* Displays a loading state while the last visited tab is being restored.
* **Bug Fixes**
* Closing deleted chat tabs now clears their saved history.
* **Tests**
* Added coverage for Explorer tab restoration, loading states, and stale
history cleanup.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Joshen Lim
ad30c04e0e