Add total litter collected display to user profile

- Updated backend userService to calculate total litter collected across all attended events
- Added totalLitterCollected field to UserProfile interface
- Added new statistics card showing total litter collected in kg
- Updated profile grid layout to accommodate 5 statistics cards
- Displays litter collected with 1 decimal place precision

START_SERVERS.md

@@ -0,0 +1,54 @@
+# Starting the Application
+
+## Backend Server
+
+Open a terminal and run:
+
+```bash
+cd server
+npm run dev
+```
+
+The backend server should start on `http://localhost:3005`
+
+You should see output like:
+```
+Server running on port 3005
+Connected to database
+```
+
+## Frontend Development Server
+
+Open another terminal and run:
+
+```bash
+npm run dev
+```
+
+The frontend should start on `http://localhost:5173`
+
+## Troubleshooting
+
+### Backend won't start
+- Check if port 3005 is already in use: `lsof -ti:3005`
+- Check database connection in `server/.env`
+- Run `cd server && npm install` to ensure dependencies are installed
+
+### Frontend won't start
+- Check if port 5173 is already in use
+- Run `npm install` to ensure dependencies are installed
+- Check `.env.local` for correct API URL
+
+### "Server returned non-JSON response" error
+- This means the backend server is not running
+- Start the backend server first (see above)
+- Check that `VITE_API_BASE_URL` in `.env.local` matches your backend URL
+
+## Quick Check
+
+Test if backend is running:
+```bash
+curl http://localhost:3005/api/events
+```
+
+Should return JSON with events list.