Fix Docker build: use esbuild for backend bundling, ESM format

Dockerfile

@@ -16,7 +16,7 @@ WORKDIR /app
 COPY trigo-web/ ./
 
 # Install build tools globally
-RUN npm install -g tsx jison typescript
+RUN npm install -g tsx jison typescript esbuild
 
 # Install dependencies
 # Root: production only (skip onnxruntime-node which requires native compilation)
@@ -32,8 +32,8 @@ RUN tsx tools/buildJisonParser.ts
 # Build frontend (generates dist folder)
 RUN cd app && npm run build
 
-# Build backend TypeScript - use global tsc directly
-RUN cd backend && tsc
+# Build backend with esbuild (handles ESM imports without .js extensions)
+RUN esbuild backend/src/server.ts --bundle --platform=node --target=node20 --format=esm --outfile=backend/dist/server.js --external:express --external:socket.io --external:cors --external:dotenv --external:uuid
 
 # Set environment variables for Hugging Face Spaces
 ENV PORT=7860

trigo-web/backend/package.json

@@ -3,11 +3,11 @@
 	"version": "1.0.0",
 	"type": "module",
 	"description": "Backend server for Trigo game",
-	"main": "dist/backend/src/server.js",
+	"main": "dist/server.js",
 	"scripts": {
 		"dev": "nodemon --watch src --exec tsx src/server.ts",
 		"build": "tsc",
-		"start": "node dist/backend/src/server.js",
+		"start": "node dist/server.js",
 		"test": "echo \"Error: no test specified\" && exit 1"
 	},
 	"keywords": [

trigo-web/backend/tsconfig.json

@@ -1,7 +1,7 @@
 {
 	"compilerOptions": {
 		"target": "ES2020",
-		"module": "ESNext",
+		"module": "Node20",
 		"lib": ["ES2020"],
 		"outDir": "./dist",
 		"rootDir": "../",
@@ -9,7 +9,7 @@
 		"esModuleInterop": true,
 		"skipLibCheck": true,
 		"forceConsistentCasingInFileNames": true,
-		"moduleResolution": "bundler",
+		"moduleResolution": "Node20",
 		"resolveJsonModule": true,
 		"declaration": true,
 		"declarationMap": true,
@@ -18,12 +18,12 @@
 		"allowJs": true,
 		"noImplicitAny": false
 	},
-	"include": ["src/**/*", "../inc/**/*"],
-	"exclude": ["node_modules", "dist", "../inc/trigo/parserInit.ts", "../inc/tgn/tgn.jison.cjs", "../inc/config.ts"],
+	"include": ["src/**/*", "../inc/trigo/**/*"],
+	"exclude": ["node_modules", "dist", "../inc/trigo/parserInit.ts"],
 	"ts-node": {
 		"esm": true,
 		"compilerOptions": {
-			"module": "ESNext"
+			"module": "Node20"
 		}
 	}
 }