Feature/mainpage UI

[yen2i]

✅ Pull Request Checklist

• PR Title: [Feature/Fix/Refactor...] Brief summary of the work (branch name) #IssueNumber
• Verify that the commit messages are appropriate.
• Confirm that the request is made to the correct branch.
• Add Assignees and Labels.
• If there is someone who needs to review specific details, add them as a Reviewer.
• After the PR is approved, delete the branch.

🔄 Changes

This PR does the following:

• This is the main screen page that will appear after logging in.
• It includes buttons that can be moved to four functions.
• There is a main logo and a welcome phrase.

📎 Reason for Changes

• I created a new page to go to 4 features after logging in.

👨🏻‍💻 Test Checklist

• After running the page, I checked the button reaction.

📌 Additional Changes or Important Notes

[hajinki]

Your main code is very good, but it looks like a design change is needed