feat: implement multi-user live workout rooms and real-time sync (#1023)

[knoxiboy]

📌 Related Issue

Fixes #1023

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📝 Description

This PR implements Multi-User Live Workout Rooms, real-time stat synchronization via Socket.IO, competitive modes, activity leaderboards, WebRTC voice status indicator, and spectator mode.

🔹 What has been changed?

• Created MultiplayerRoomScreen.tsx as a premium dashboard lobby allowing room creation/joining, mode selection, live camera grids, and real-time multiplayer workout tracking.
• Added room handlers (room:create, room:join, room:update-stats, room:start-game) to server/src/socket/handlers.js to manage multi-user synchronization.
• Added support for game modes: Race Mode (first to 50 reps), Endurance Mode (survival), and Form Battle (highest score).
• Linked the multiplayer screen route and transitions inside App.tsx and mounted a "Live Battle" action button on the WelcomeScreen.tsx hero.
• Fixed a missing lucide icon import (ShieldAlert) in WorkoutScreen.tsx.
• Installed socket.io-client dependency.

🔹 Why are these changes needed?

To gamify and introduce social elements to SpectraX, allowing users to connect, motivate, and compete with friends in real-time.

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🛠️ Type of Change

• 🐛 Bug Fix
• ✨ New Feature
• 🎨 UI/UX Improvement
• 📖 Documentation Update
• ⚡ Performance Improvement
• 🔧 Refactoring
• 💥 Breaking Change

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🧪 Testing

✅ Tests Performed

• Tested locally
• Build runs successfully
• No console errors
• Responsive design checked
• Existing functionality verified

🌐 Browsers Tested

• Chrome
• Firefox

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📷 Screenshots / Demo (if applicable)

(Lobby grid showing player status, countdowns, and real-time rep counts)

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📋 Checklist

• I have read the project's CONTRIBUTING guidelines
• My code follows the project style guidelines
• I have performed a self-review of my code
• I have tested my changes locally
• I have added/updated documentation where necessary
• My changes do not introduce new warnings or errors
• This PR is linked to an existing issue

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[knoxiboy]

@Somil450 Please review and merge the pr

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