Migrate database from MySQL to Supabase PostgreSQL

- Added @supabase/supabase-js client library
- Rewrote database.js to use Supabase API
- Updated server.js health check for Supabase
- Updated db.config.example.js with Supabase format
- Created comprehensive SUPABASE_SETUP.md guide
- Added SQL schema files for easy deployment
- Updated README_DB_CONFIG.md for Supabase

Benefits:
- Managed PostgreSQL database
- Built-in Row Level Security
- Real-time capabilities
- Easy monitoring via dashboard
- Free tier for development

db.config.example.js

@@ -1,13 +1,18 @@
-// Database Configuration File
-// IMPORTANT: This file contains sensitive credentials and should NEVER be committed to git
-// Copy this file to db.config.js and update with your actual database credentials
+// Database Configuration File - EXAMPLE
+// Copy this file to db.config.js and fill in your actual Supabase credentials
+// DO NOT commit db.config.js to git - it's in .gitignore
 
+// Supabase Configuration
+// Get these values from your Supabase project dashboard:
+// 1. Go to https://app.supabase.com
+// 2. Select your project
+// 3. Go to Project Settings → API
 module.exports = {
-    host: 'your-database-host.com',
-    user: 'your-database-username',
-    password: 'your-secure-password',
-    database: 'your-database-name',
-    waitForConnections: true,
-    connectionLimit: 10,
-    queueLimit: 0
+    supabaseUrl: 'https://xxxxxxxxxxxxx.supabase.co', // Your Supabase project URL
+    supabaseAnonKey: 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...', // Your Supabase anon/public key
+    supabasePassword: 'your_database_password_here', // Your database password
+    
+    // Optional: Direct PostgreSQL connection string
+    // Found in Project Settings → Database → Connection String
+    postgresConnectionString: 'postgresql://postgres:your_password@db.xxxxxxxxxxxxx.supabase.co:5432/postgres'
 };