feat: implement realtime check-in and dashboard optimizations

[saidai-bhuvanesh]

Closes #383

📝 Description

This PR introduces realtime attendee synchronization, dashboard performance optimizations, and organizer workflow improvements for the EventOne platform using Socket.IO and frontend rendering optimizations.

🔗 Related Issue

Closes #YOUR_GSSOC_ISSUE_NUMBER

🛠️ Changes

1. Frontend Improvements

• Dashboard Rendering: Optimized the organizer dashboard rendering pathways.
• Search Responsiveness: Improved attendee search responsiveness inside the event management panels.
• Avoid Rerenders: Memoized attendee list views to significantly reduce unnecessary re-renders.
• Realtime Feedback: Added active connection status tracking and feedback to the user interface.

2. Backend Improvements

• Socket.IO Sync: Implemented reliable Socket.IO realtime synchronization for event registration changes.
• Check-In Workflows: Revamped organizer check-in workflows to support multi-key verification and authorization.
• API Efficiency: Consolidated redundant queries and optimized backend endpoint payload structures.
• Waitlist Promotions: Automated waitlist promotions atomically when reservations are cancelled.

3. Performance Improvements

• Lag Reduction: Reduced dashboard rendering lag during search filter inputs.
• Realtime Responsiveness: Optimized latency for socket broadcasts to connected event rooms.
• Smooth UI Interactions: Improved organizer interaction smoothness throughout the dashboard panels.

🧪 How to Test

1. Run both the frontend and backend servers locally.
2. Verify that Socket.IO initializes correctly on server startup.
3. Open the Organizer Dashboard and a Customer session in separate browser windows.
4. Register a customer for an event and verify the realtime attendee list updates on the dashboard.
5. Perform an attendee check-in and verify that the check-in status syncs instantly on the dashboard.
6. Test the dashboard attendee search input and verify that there is no typing keystroke lag.
7. Run the backend test suites using npm run test.
8. Run the production build in the frontend directory using npm run build to verify compilation.

✅ Contributor Checklist

• My code follows the project's existing style
• I have tested my changes locally
• I have linked the related issue above
• My PR title follows Conventional Commits format (e.g. feat: add scroll button)
• I used a feature branch (not main)
• I have NOT used AI tools to write the core logic without disclosure

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[github-actions]

👋 Thanks for opening a PR, @saidai-bhuvanesh!

Your PR has entered the 🎯 EventOne GSSoC PR Review Pipeline.

🟢 GSSoC PR detected — your PR will be routed to an approved GSSoC mentor for Stage 2 review.

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EventOne × GSSoC Automated Pipeline

[github-actions]

❌ PR Format Check — Failed — Please Fix Below

Hi @saidai-bhuvanesh! Please fix the issues below before your PR can proceed to mentor review.

❌ Must Fix Before Proceeding

❌ Issue #383 is not assigned to you (@saidai-bhuvanesh) — You must be assigned to the issue before submitting a PR.

Comment /assign on Issue #383 or ask a maintainer to assign it to you.

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📋 EventOne PR Guidelines (click to expand)

Title format — Conventional Commits:
feat: · fix: · docs: · style: · refactor: · test: · chore: · perf:

Always link an issue: Closes #number

Use a feature branch — never PR directly from main

Write your own description — AI-generated content = gssoc:ai-slop label

EventOne × GSSoC Pipeline — Stage 1 Automated Check