Add profile screen component for bottom navigation

[TrentIndeed]

Motivation

• Provide a full-profile screen UI to be shown when the bottom navigation's profile icon is active.
• Include mock activity and volume data to demonstrate charts and stats for the profile view.
• Offer reusable small components to keep the layout modular and re-usable across the app.

Description

• Add a new file src/App.jsx that exports the App component implementing the profile screen layout with Tailwind classes and lucide-react icons.
• Implement App with activeTab state and mock data arrays activityData and volumeData used to render the weekly activity chart and muscle-group volume bars.
• Add reusable presentational components StatCard, MenuItem, and NavIcon used by the profile screen.
• Include a bottom navigation with Home, Dumbbell, central Plus action, Compass, and User icons and wiring so the profile tab is active by default.

Testing

• No automated tests are configured in the repository, so no automated tests were run.

---

Codex Task