Add .dockerignore to optimize build context

.dockerignore

@@ -0,0 +1,46 @@
+# Dependencies
+node_modules/
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Development
+.env
+.env.local
+.env.*.local
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Git
+.git/
+.gitignore
+
+# Build artifacts (we copy these explicitly when needed)
+frontend/dist/
+backend/dist/
+
+# Temp files
+temp/
+*.tmp
+
+# Documentation
+README.md
+*.md
+!package*.json
+
+# Test files
+*.test.ts
+*.test.js
+*.spec.ts
+*.spec.js
+__tests__/
+__mocks__/