feat: create profile tab

[yc08]

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[Copilot]

Pull Request Overview

This PR introduces a new profile tab to the frontend, enabling users to view their AtCoder profile data through an interactive input and corresponding UI components, and adds backend endpoints to support profile retrieval and proxy AtCoder API calls.

• Added a “Profile” tab and associated components (CardHeader, Profile, Body) in the frontend.
• Updated frontend styles to support the new username input and adjusted animations.
• Updated backend endpoints and added createProfileJson in the AtCoder utility along with related proxy endpoints.

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
frontend/src/App.js	Added profile tab, new components for user input, profile display, and profile fetching with debounce logic.
frontend/src/App.css	Introduced new styles for the user input box and disabled a pulsing animation.
backend/package.json	Upgraded node-fetch version to support newer functionality.
backend/netlify/profile.js	Added a Netlify function to handle profile requests using createProfileJson.
backend/index.js	Introduced new proxy endpoints and a profile endpoint integrating the new profile functionality.
backend/atcoder.js	Added createProfileJson to fetch profile data from AtCoder and manage local caching.

Files not reviewed (1)

• backend/package-lock.json: Language not supported

Comments suppressed due to low confidence (1)

backend/atcoder.js:40

• The fs module is used in createProfileJson but is not imported. Please add 'const fs = require("fs");' at the top of the file.

    const profileDir = path.join(saveDir, "profiles");