feat: add toolbox contract shell and testkit

package.json

@@ -0,0 +1,49 @@
+{
+  "name": "@add-ideas/toolbox-sdk-workspace",
+  "version": "0.1.0",
+  "private": true,
+  "description": "A small, framework-neutral toolbox contract with a React application shell.",
+  "license": "Apache-2.0",
+  "repository": {
+    "type": "git",
+    "url": "git+https://git.add-ideas.de/zemion/toolbox-sdk.git"
+  },
+  "type": "module",
+  "workspaces": [
+    "packages/*"
+  ],
+  "engines": {
+    "node": ">=20"
+  },
+  "scripts": {
+    "build": "npm run build -w @add-ideas/toolbox-contract && npm run build -w @add-ideas/toolbox-shell-react && npm run build -w @add-ideas/toolbox-testkit",
+    "clean": "npm run clean --workspaces --if-present",
+    "typecheck": "npm run typecheck --workspaces --if-present",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "lint": "eslint . --max-warnings=0",
+    "format": "prettier --check .",
+    "format:write": "prettier --write .",
+    "check": "npm run typecheck && npm run lint && npm run format && npm test && npm run build"
+  },
+  "devDependencies": {
+    "@eslint/js": "^10.0.1",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
+    "@types/node": "^25.8.0",
+    "@types/react": "^19.2.14",
+    "@types/react-dom": "^19.2.3",
+    "ajv": "^8.20.0",
+    "eslint": "^10.4.0",
+    "eslint-plugin-react-hooks": "^7.1.1",
+    "globals": "^17.6.0",
+    "jsdom": "^29.1.1",
+    "prettier": "^3.8.3",
+    "react": "^19.2.6",
+    "react-dom": "^19.2.6",
+    "typescript": "^6.0.3",
+    "typescript-eslint": "^8.59.3",
+    "vitest": "^4.1.6"
+  },
+  "packageManager": "npm@11.17.0"
+}