fix(api): add CORS middleware for frontend browser integrationFix backend cors support

[Arijit429]

Closes #415

🚀 Summary

This PR adds CORS middleware support to the FastAPI backend to enable seamless browser-based frontend integration.

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🐛 Problem

The frontend is served separately (for example from:

http://127.0.0.1:5500

) and communicates with the backend API running on:

http://127.0.0.1:8000

This triggers browser preflight OPTIONS requests.

Without proper CORS configuration, these requests fail with:

400 Bad Request

which blocks all frontend-to-backend communication.

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✨ Fix

Added CORSMiddleware in:

api/main.py

Allowed local frontend origins:

http://127.0.0.1:5500
http://localhost:5500

Also enabled:

• all methods
• all headers
• credential support

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🎯 Production Impact

This significantly improves deployment readiness by enabling:

• browser frontend integration
• local development workflows
• docker-based frontend/backend separation
• future cloud deployment compatibility

This is an important production-readiness improvement for the project architecture.

[Arijit429]

Continuing the production-readiness roadmap, this PR focuses on frontend-backend deployment compatibility by enabling proper browser CORS support for separated frontend workflows.