Add Docker Compose configuration and environment files for local and production setups

- Created docker-compose.docker-local.yml for local testing of frontend and backend services.
- Added .env.development for development environment configuration.
- Introduced .env.docker-local for local Docker environment settings.
- Added .env.production for production environment configuration for Synology deployment.

code/websites/pokedex.online/server/utils/env-validator.js

@@ -9,6 +9,13 @@
  * Required environment variables for production
  */
 const REQUIRED_ENV_VARS = {
+  // Deployment Configuration
+  DEPLOYMENT_TARGET: {
+    required: true,
+    description: 'Deployment environment (dev, docker-local, production)',
+    validate: val => ['dev', 'docker-local', 'production'].includes(val)
+  },
+
   // Server Configuration
   NODE_ENV: {
     required: true,
@@ -22,6 +29,34 @@ const REQUIRED_ENV_VARS = {
       !isNaN(parseInt(val)) && parseInt(val) > 0 && parseInt(val) < 65536
   },
 
+  // Frontend URL for CORS
+  FRONTEND_URL: {
+    required: true,
+    description: 'Frontend URL for CORS',
+    validate: (val, env) => {
+      if (!val) return false;
+      
+      // Validate that FRONTEND_URL matches DEPLOYMENT_TARGET (if set)
+      const target = env?.DEPLOYMENT_TARGET;
+      if (!target) return true; // Skip validation if target not set yet
+      
+      if (target === 'dev' && !val.includes('localhost:5173')) {
+        console.error('⚠️  FRONTEND_URL should be http://localhost:5173 for dev target');
+        return false;
+      }
+      if (target === 'docker-local' && !val.includes('localhost:8099')) {
+        console.error('⚠️  FRONTEND_URL should be http://localhost:8099 for docker-local target');
+        return false;
+      }
+      if (target === 'production' && !val.includes('app.pokedex.online')) {
+        console.error('⚠️  FRONTEND_URL should be https://app.pokedex.online for production target');
+        return false;
+      }
+      
+      return true;
+    }
+  },
+
   // Optional but recommended for production
   SESSION_SECRET: {
     required: false,
@@ -31,14 +66,6 @@ const REQUIRED_ENV_VARS = {
         ? 'SESSION_SECRET should be at least 32 characters for security'
         : null
   },
-  FRONTEND_URL: {
-    required: false,
-    description: 'Frontend URL for CORS (required in production)',
-    warn: (val, env) =>
-      env.NODE_ENV === 'production' && !val
-        ? 'FRONTEND_URL should be set in production for proper CORS'
-        : null
-  },
 
   // Challonge OAuth (optional)
   CHALLONGE_CLIENT_ID: {
@@ -110,8 +137,10 @@ export function validateOrExit(exitOnError = true) {
 
   // Print validation results
   console.log('\n🔍 Environment Validation:');
+  console.log(`   DEPLOYMENT_TARGET: ${process.env.DEPLOYMENT_TARGET || 'not set'}`);
   console.log(`   NODE_ENV: ${process.env.NODE_ENV || 'not set'}`);
   console.log(`   PORT: ${process.env.PORT || 'not set'}`);
+  console.log(`   FRONTEND_URL: ${process.env.FRONTEND_URL || 'not set'}`);
 
   // Show errors
   if (result.errors.length > 0) {
@@ -149,7 +178,11 @@ export function validateOrExit(exitOnError = true) {
  * @returns {Object} Configuration object
  */
 export function getConfig() {
+  const deploymentTarget = process.env.DEPLOYMENT_TARGET || 'dev';
+  const frontendUrl = process.env.FRONTEND_URL;
+  
   return {
+    deploymentTarget,
     nodeEnv: process.env.NODE_ENV || 'development',
     port: parseInt(process.env.PORT || '3001'),
     isProduction: process.env.NODE_ENV === 'production',
@@ -165,16 +198,10 @@ export function getConfig() {
       )
     },
 
-    // CORS
+    // CORS - Single origin based on deployment target
     cors: {
-      origin:
-        process.env.NODE_ENV === 'production'
-          ? process.env.FRONTEND_URL
-          : [
-              'http://localhost:5173',
-              'http://localhost:5174',
-              'http://localhost:5175'
-            ]
+      origin: frontendUrl,
+      credentials: true
     },
 
     // Security
@@ -192,3 +219,8 @@ export function getConfig() {
     }
   };
 }
+
+// Run validation when executed directly
+if (import.meta.url === `file://${process.argv[1]}`) {
+  validateOrExit();
+}