…4542)

* Refactor DefaultChat component to display a simple welcome message instead of mock chat interface onboarding text

* Add last visited workspace functionality

- Implemented localStorage management for the last visited workspace in DefaultChat and WorkspaceChat components.
- Updated UserButton to clear last visited workspace on logout.
- Refactored workspace navigation to prioritize last visited workspace if available.

* Refactor workspace fetching & last visited workspace logic into one useEffect

* Enhance loading state in DefaultChat component with skeleton UI elements for improved user experience

* minor UI spacing changes

* refactor order for guard clauses for early exit conditions

* move last known to end of getWorkspace loader

* languages for PR #4542 (#4550)

* languages for PR #4542

* Drop welcome message keys from translations

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Co-authored-by: timothycarambat <rambat1010@gmail.com>