✨Feat: add mock data fallback for empty API responses

[woojo230]

#️⃣ Related Issue

e.g. Closes #32

📝 Description

• add mock data fallback for empty API responses
• add main logo

📌 Notes

✅ Checklist

• Have you selected the reviewers?
• Have you assigned yourself?
• Is the target branch correct?
• Does this PR follow the project conventions?
• Does the code run without errors locally?
• Have unnecessary comments been removed?
• Is the code style consistent?

📷 Screenshots (Optional)

💬 Review Requests (Optional)

e.g. I'm looking for a better name for method XXX. Any suggestions?

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