[WIP] Enable CORS for frontend access to backend API

[Copilot]

Plan: Enable CORS on Backend API

• Explore repository structure and understand current implementation
• Create branch copilot/enable-cors-backend
• Update backend/src/server.js to use CORS_ORIGIN environment variable
• Add OPTIONS preflight handler with app.options('*', cors(corsOptions))
• Add explicit header setting middleware for Access-Control-Allow-Origin
• Verify cors package is in backend/package.json (already present at version ^2.8.5)
• Test the changes by running the server locally
• Update .env.example with CORS_ORIGIN variable
• Run linter to ensure code quality
• Create PR with proper documentation

Current Status: CORS package is already present in dependencies. Server.js already has CORS configured but uses FRONTEND_URL env variable. Need to update to use CORS_ORIGIN with default fallback to 'https://idweb3.sliplane.app' and add proper OPTIONS handling.

Original prompt

Enable CORS in the backend API to allow the frontend origin https://idweb3.sliplane.app to access the API. Changes to make:

1. Add the 'cors' package to backend dependencies (backend/package.json) if not present.
2. Modify the backend server entry file to use the cors middleware and to explicitly set Access-Control-Allow-Origin to the frontend domain. The middleware should also handle OPTIONS preflight requests and allow common headers (Content-Type, Authorization, X-Requested-With) and credentials if necessary.

Implementation details:

• Detect the backend entry file by searching for app.listen(...) or typical server entry in backend/ (e.g., backend/src/server.js, backend/index.js). Modify that file to require('cors') and insert the middleware after app initialization and before routes.
• Use an environment variable CORS_ORIGIN (fallback default to 'https://idweb3.sliplane.app').
• Add app.options('*', cors(corsOptions)); and a small middleware to set headers and handle OPTIONS returning 204.

Files to change or create:

• Create branch: copilot/enable-cors-backend
• Update backend/package.json to include "cors": "^2.8.5" in dependencies (preserve existing dependencies).
• Update the backend server entry file (detected path) with the cors usage as described.

PR description (include instructions):

• Title: Enable CORS on idweb3-api backend to allow frontend origin
• Body: explain changes, how to install deps (cd backend && npm install), redeploy, verify with curl -i https://idweb3-y8qpxt.sliplane.app/health expecting Access-Control-Allow-Origin header, and recommend setting CORS_ORIGIN env var in Sliplane.

Do NOT include any secrets.

This pull request was created as a result of the following prompt from Copilot chat.

Enable CORS in the backend API to allow the frontend origin https://idweb3.sliplane.app to access the API. Changes to make:

1. Add the 'cors' package to backend dependencies (backend/package.json) if not present.
2. Modify the backend server entry file to use the cors middleware and to explicitly set Access-Control-Allow-Origin to the frontend domain. The middleware should also handle OPTIONS preflight requests and allow common headers (Content-Type, Authorization, X-Requested-With) and credentials if necessary.

Implementation details:

• Detect the backend entry file by searching for app.listen(...) or typical server entry in backend/ (e.g., backend/src/server.js, backend/index.js). Modify that file to require('cors') and insert the middleware after app initialization and before routes.
• Use an environment variable CORS_ORIGIN (fallback default to 'https://idweb3.sliplane.app').
• Add app.options('*', cors(corsOptions)); and a small middleware to set headers and handle OPTIONS returning 204.

Files to change or create:

• Create branch: copilot/enable-cors-backend
• Update backend/package.json to include "cors": "^2.8.5" in dependencies (preserve existing dependencies).
• Update the backend server entry file (detected path) with the cors usage as described.

PR description (include instructions):

• Title: Enable CORS on idweb3-api backend to allow frontend origin
• Body: explain changes, how to install deps (cd backend && npm install), redeploy, verify with curl -i https://idweb3-y8qpxt.sliplane.app/health expecting Access-Control-Allow-Origin header, and recommend setting CORS_ORIGIN env var in Sliplane.

Do NOT include any secrets.

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