fix: Enable Corepack for Yarn 4.x compatibility in Docker build

- Enable Corepack in Dockerfile to support packageManager field
- Fix lint script to use TypeScript checking instead of invalid yarn check
- Remove manual yarn installation from Dockerfile since Corepack handles it

Dockerfile

@@ -1,8 +1,8 @@
 # Multi-stage build for Node.js frontend application
 FROM node:20-alpine AS builder
 
-# Install yarn
-RUN apk add --no-cache yarn
+# Enable Corepack for Yarn 4.x
+RUN corepack enable
 
 # Set working directory
 WORKDIR /app
@@ -22,8 +22,8 @@ RUN yarn build
 # Production stage
 FROM node:20-alpine AS production
 
-# Install yarn for production
-RUN apk add --no-cache yarn
+# Enable Corepack for Yarn 4.x
+RUN corepack enable
 
 # Create app user
 RUN addgroup -g 1001 -S nodejs

package.json

@@ -8,7 +8,7 @@
 		"build": "vite build && esbuild server/index.ts --platform=node --packages=external --bundle --format=esm --outdir=dist",
 		"start": "NODE_ENV=production node dist/index.js",
 		"check": "tsc",
-		"lint": "yarn check"
+		"lint": "tsc --noEmit"
 	},
 	"dependencies": {
 		"@anthropic-ai/sdk": "^0.37.0",