Expand Overview stories with empty, loading, and error states

[1012Charan]

Adds 3 Storybook stories for the Overview component:

• EmptyState (shows the UI when there's no data available)
• LoadingState (shows a spinner while data is being fetched)
• ErrorState (simulates when data fails to load)

Screenshots for new stories :
EmptyState

LoadingState

ErrorState

Note: I noticed that the Empty, Loading, and Error states all look quite similar in Storybook — they seem to show the same fallback message or UI. I'm assuming this is expected because the Overview component handles these cases in a similar way with mock data, but please let me know if I might have missed something!

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: 1012Charan / name: Charan Vengala (752234f, d992d4a)

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[joaquimrocha]

Thanks @1012Charan . Can you adapt the commit title to be more consistent with our current format:
frontend: Expand Overview stories with empty, loading, and error states

[1012Charan]

Thanks @joaquimrocha, I've updated the commit message as suggested. Please let me know if anything else is needed.

[skoeva]

Looks solid, would be nice to have screenshots in the description for the new stories

Also good to rebase against main to pull the latest changes

[1012Charan]

Thanks for the suggestion @skoeva! I've updated this branch added the screenshots, but I noticed that all three states — Empty, Loading, and Error — look almost the same in Storybook. I’m not sure if that’s okay or if I might have missed something, so please let me know if any changes are needed!